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Union and union all in sql server   Part 17
 
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In this video we will learn about the 1. Purpose of UNION and UNION ALL 2. Difference between UNION and UNION ALL 3. Difference between JOIN and UNION Text version of the video http://csharp-video-tutorials.blogspot.com/2012/08/union-and-union-all-in-sql-server-part.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-17-union-and-union-all.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 276240 kudvenkat
SQL UNION, INTERSECT, EXCEPT
 
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Jamie King of Neumont University demonstrating UNION, INTERSECT, and EXCEPT.
Views: 48309 Jamie King
SQL Intersect, Union, Union All, Minus, and Except
 
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This video explains how the keywords INTERSECT, UNION, UNION ALL, MINUS, and EXCEPT are used in SQL.
Views: 48263 1Keydata
15 of 15 SQL Basics with Oracle - Traditional set operators: UNION, INTERSECT & MINUS
 
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This video gives examples of three set operators: UNION, INTERSECT, MINUS. The union compatible rule is also explained. Set operators are used when output comes from more than one SQL statement. (15 of 15) There is also an "Advanced SQL" series. (Search for "databasemec" for tutorials using SQL Server.)
Views: 12783 Jennifer Kreie
SelectTec | Aula Nº 33 | Union / Union ALL - Oracle SQL Developer
 
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Sintax select coluna1 from tabela1 union select coluna2 from tabela2; select coluna1 from tabela1 union all select coluna2 from tabela2 where expressão...
Views: 1097 SelectTec
ORDER BY Clause in Oracle | Oracle Tutorials for Beginners
 
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Oracle Tutorials for Beginners ORDER BY Clause In Oracle ORDER BY Clause in SQL Oracle Tutorials for Beginners Oracle SQL Introduction #Oracle Tutorisla for Beginners Oracle for Beginners Oracle plsql tutorial for Beginners Oracle plsql tutorial for Beginners Oracle plsql tutorial for Beginners ORDER BY in Oracle SQL ORDER BY in Oracle SQL ORDER BY in Oracle SQL NULLS FIRST in Oracle NULLS FIRST in Oracle NULLS LAST in Oracle NULLS LAST in Order by Clause how order by clause works in oracle oracle order by date oracle sort varchar2 alphabetically oracle order by case multiple columns oracle sql order by specific values order by in oracle w3schools sql order by multiple columns oracle order by column not in select order by in oracle w3schools oracle order by multiple columns oracle sql order by specific values how order by clause works in oracle oracle order by date oracle order by group by sql order by alphabetical order by sql
Views: 638 Oracle PL/SQL World
Oracle Tutorial - Set Operators UNION & UNION ALL
 
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Oracle Tutorials - Set Operators UNION and UNION ALL
Views: 77 Tech Acad
IN vs Union All in SQL Server
 
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One option for improving query performance is to rewrite the query in order to obtain a completely different execution plan. In this episode we look at how it's possible to rewrite queries with correlated subqueries into derived table syntax and examine what causes the difference in performance. Subscribe and turn on notifications to never miss a weekly video: https://www.youtube.com/c/bertwagner?sub_confirmation=1 Related blog post with example code: https://bertwagner.com/2019/04/23/correlated-subqueries-vs-derived-tables/ Follow me on Twitter: https://twitter.com/bertwagner
Views: 679 Bert Wagner
How to Join 3 tables in 1 SQL query
 
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Get your first month on the Joes 2 Pros Academy for just $1 with code YOUTUBE1. Visit http://www.joes2pros.com Offer expires July 1, 2015 From the newly released 2 Disc DVD set (SQL Queries Joes 2 Pros Vol2) this video shows how to join 3 tables in 1 query.
Views: 267508 Joes2Pros SQL Trainings
SQL Union and Union All Operators - Tutorial w/ Derby Database
 
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http://www.zaneacademy.com | download source code @ http://sites.fastspring.com/zaneacademy/product/all | 00:00 What is an example of using Union and union all operators in a derby database? | 04:15 What is the SQL UNION Operator? | 05:10 What is an example of the SQL UNION Operator? | 07:25 What is the SQL UNION ALL Operator? | 07:38 What is the difference between the SQL Union and Union All operators? | 08:00 What is an example of the SQL UNION All Operator?
Views: 1963 zaneacademy
SQL Inner Join Multiple Tables with SUM Tutorial - SQL 2008/2012/2016/2017
 
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Use inner joins with multiple tables to create reports. Uses aliases, and the SUM aggregate function to demonstrate the flexibility of the join statement. Get the SQL script to create the database and run the exercies in the video here: https://www.qewbi.com/sql/scripts/qewbijoins.zip
Views: 149611 Edward Kench
SQL Tutorial in Oracle - 4 NULL, LIKE, DISTINCT, ORDER BY
 
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SQL SELECT statement is used to fetch the data from a database table which returns data in the form of result table. These result tables are called result-sets. The LIKE operator is used in a WHERE clause to search for a specified pattern in a column. In SQL, wildcard characters are used with the SQL LIKE operator. SQL wildcards are used to search for data within a table. With SQL, the wildcards are: Wildcard Description % A substitute for zero or more characters _ A substitute for a single character [charlist] Sets and ranges of characters to match [^charlist] or [!charlist] Matches only a character NOT specified within the brackets Check out our website: http://www.telusko.com Follow Telusko on Twitter: https://twitter.com/navinreddy20 Follow on Facebook: Telusko : https://www.facebook.com/teluskolearnings Navin Reddy : https://www.facebook.com/navintelusko Follow Navin Reddy on Instagram: https://www.instagram.com/navinreddy20 Subscribe to our other channel: Navin Reddy : https://www.youtube.com/channel/UCxmkk8bMSOF-UBF43z-pdGQ?sub_confirmation=1 Telusko Hindi : https://www.youtube.com/channel/UCitzw4ROeTVGRRLnCPws-cw?sub_confirmation=1
Views: 19933 Telusko
SQL Union and Union All - SQL Training Online
 
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Union and Union All are very similar, but if you don’t understand the differences, it can cause trouble. In this video I do a quick demonstration of the Union and Union All Function. READ THE ORIGINAL ARTICLE WITH SQL SCRIPTS HERE http://www.sqltrainingonline.com/sql-server-union-all/ YOUTUBE NEWS UPDATES http://www.youtube.com/user/sqltrainingonline VISIT SQLTRAININGONLINE.COM FOR TONS MORE VIDEO NEWS & TIPS http://www.sqltrainingonline.com SUBSCRIBE FOR OTHER SQL TIPS AND NEWS! http://www.youtube.com/subscription_center?add_user=sqltrainingonline SUBSCRIBE TO OUR EMAIL LIST! http://www.sqltrainingonline.com LET'S CONNECT! Google+: http://gplus.to/SQLTrainingOnline Facebook: http://facebook.com/SQLTrainingOnline Twitter: http://twitter.com/sql_by_joey Linkedin: http://linkedin.com/in/joeyblue SQLTrainingOnline: http://www.sqltrainingonline.com
Views: 4060 Joey Blue
Learn Basic SQL Commands: SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY
 
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This SQL tutorial introduces the basic elements of SQL. By the end of this tutorial, you will be able to write simple queries to retrieve data out of a relational database. View the 1Keydata SQL Tutorial online at http://www.1keydata.com/sql/sql.html. 0:34 Database basics 1:01 SELECT...FROM 1:47 WHERE 2:24 ORDER BY 3:28 GROUP BY 5:20 HAVING
Views: 82692 1Keydata
SQL SELECT ORDER BY
 
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Sorting and ordering in SQL Server using ORDER BY. We demonstrating sorting, sub sorting, ascending, descending and using an alias to sort.
Views: 99 Jon Jensen
Grouping Sets in SQL Server
 
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grouping sets examples in sql server sql server grouping sets order by grouping sql server 2008 grouping sets example sql server group by union all Grouping sets is a new feature introduced in SQL Server 2008. Let us understand Grouping sets with an example. We want to calculate Sum of Salary by Country and Gender. We can very easily achieve this using a Group By query as shown below Select Country, Gender, Sum(Salary) as TotalSalary From Employees Group By Country, Gender Within the same result set we also want Sum of Salary just by Country. To achieve the above result we could combine 2 Group By queries using UNION ALL as shown below. Select Country, Gender, Sum(Salary) as TotalSalary From Employees Group By Country, Gender UNION ALL Select Country, NULL, Sum(Salary) as TotalSalary From Employees Group By Country Within the same result set we also want Sum of Salary just by Gender. We can achieve this by combining 3 Group By queries using UNION ALL as shown below Select Country, Gender, Sum(Salary) as TotalSalary From Employees Group By Country, Gender UNION ALL Select Country, NULL, Sum(Salary) as TotalSalary From Employees Group By Country UNION ALL Select NULL, Gender, Sum(Salary) as TotalSalary From Employees Group By Gender Finally we also want the grand total of Salary. In this case we are not grouping on any particular column. So both Country and Gender columns will be NULL in the resultset. To achieve this we will have to combine the fourth query using UNION ALL as shown below. Select Country, Gender, Sum(Salary) as TotalSalary From Employees Group By Country, Gender UNION ALL Select Country, NULL, Sum(Salary) as TotalSalary From Employees Group By Country UNION ALL Select NULL, Gender, Sum(Salary) as TotalSalary From Employees Group By Gender UNION ALL Select NULL, NULL, Sum(Salary) as TotalSalary From Employees There are 2 problems with the above approach. The query is huge as we have combined different Group By queries using UNION ALL operator. This can grow even more if we start to add more groups The Employees table has to be accessed 4 times, once for every query. If we use Grouping Sets feature introduced in SQL Server 2008, the amount of T-SQL code that you have to write will be greatly reduced. The following Grouping Sets query produce the same result as the above UNION ALL query. Select Country, Gender, Sum(Salary) TotalSalary From Employees Group BY GROUPING SETS ( (Country, Gender), -- Sum of Salary by Country and Gender (Country), -- Sum of Salary by Country (Gender) , -- Sum of Salary by Gender () -- Grand Total ) The order of the rows in the result set is not the same as in the case of UNION ALL query. To control the order use order by as shown below. Select Country, Gender, Sum(Salary) TotalSalary From Employees Group BY GROUPING SETS ( (Country, Gender), -- Sum of Salary by Country and Gender (Country), -- Sum of Salary by Country (Gender) , -- Sum of Salary by Gender () -- Grand Total ) Order By Grouping(Country), Grouping(Gender), Gender Text version of the video http://csharp-video-tutorials.blogspot.com/2015/09/grouping-sets-in-sql-server.html Slides http://csharp-video-tutorials.blogspot.com/2015/09/grouping-sets-in-sql-server_19.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 52429 kudvenkat
Order by in union with Example in SqlServer
 
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In this Tutorial i will teach you, How to get the union value from two tables. I mean to say that, i have two table and i want to get all rows of table 1 also i want to get all column of table 2 then use union with order by clause.
Views: 347 SQL
EXIST Function in SQL
 
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Join Discussion: http://www.techtud.com/video-lecture/exist-function-sql IMPORTANT LINKS: 1) Official Website: http://www.techtud.com/ 2) Virtual GATE: http://virtualgate.in/login/index.php Both of the above mentioned platforms are COMPLETELY FREE, so feel free to Explore, Learn, Practice & Share! Our Social Media Links: Facebook Page: https://www.facebook.com/techtuduniversity Facebook Group: https://www.facebook.com/groups/virtualgate Google+ Page: https://plus.google.com/+techtud/posts Last but not the least, SUBSCRIBE our YouTube channel to stay updated about the regularly uploaded new videos.
Views: 40464 Techtud
Part 2   SQL query to get organization hierarchy
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-2-sql-query-to-get-organization.html To get the best out of this video, the following concepts need to be understood first. These are already discussed in SQL Server Tutorial. 1. Self-Join - http://www.youtube.com/watch?v=qnYSN_7qwgg 2. CTE - http://www.youtube.com/watch?v=ZXB5b-7HJHk 3. Recursive CTE - http://www.youtube.com/watch?v=GGoV0wTMCg0 Here is the problem definition: 1. Employees table contains the following columns a) EmployeeId, b) EmployeeName c) ManagerId 2. If an EmployeeId is passed, the query should list down the entire organization hierarchy i.e who is the manager of the EmployeeId passed and who is managers manager and so on till full hierarchy is listed. For example, Scenario 1: If we pass David's EmployeeId to the query, then it should display the organization hierarchy starting from David. Scenario 2: If we pass Lara's EmployeeId to the query, then it should display the organization hierarchy starting from Lara. We will be Employees table for this demo. SQL to create and populate Employees table with test data Create table Employees ( EmployeeID int primary key identity, EmployeeName nvarchar(50), ManagerID int foreign key references Employees(EmployeeID) ) GO Insert into Employees values ('John', NULL) Insert into Employees values ('Mark', NULL) Insert into Employees values ('Steve', NULL) Insert into Employees values ('Tom', NULL) Insert into Employees values ('Lara', NULL) Insert into Employees values ('Simon', NULL) Insert into Employees values ('David', NULL) Insert into Employees values ('Ben', NULL) Insert into Employees values ('Stacy', NULL) Insert into Employees values ('Sam', NULL) GO Update Employees Set ManagerID = 8 Where EmployeeName IN ('Mark', 'Steve', 'Lara') Update Employees Set ManagerID = 2 Where EmployeeName IN ('Stacy', 'Simon') Update Employees Set ManagerID = 3 Where EmployeeName IN ('Tom') Update Employees Set ManagerID = 5 Where EmployeeName IN ('John', 'Sam') Update Employees Set ManagerID = 4 Where EmployeeName IN ('David') GO Here is the SQL that does the job Declare @ID int ; Set @ID = 7; WITH EmployeeCTE AS ( Select EmployeeId, EmployeeName, ManagerID From Employees Where EmployeeId = @ID UNION ALL Select Employees.EmployeeId , Employees.EmployeeName, Employees.ManagerID From Employees JOIN EmployeeCTE ON Employees.EmployeeId = EmployeeCTE.ManagerID ) Select E1.EmployeeName, ISNULL(E2.EmployeeName, 'No Boss') as ManagerName From EmployeeCTE E1 LEFT Join EmployeeCTE E2 ON E1.ManagerID = E2.EmployeeId
Views: 305738 kudvenkat
136. UNION ALL in SQL (Hindi)
 
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Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 6092 Geeky Shows
SQL Union Operator with Example in Oracle 11g(Hindi, English)
 
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SQL Tutorial for Beginners in Hindi and English SQL Union Operator with Example in Oracle 11g(Hindi, English)
Set Operators and UNION (Introduction to Oracle SQL)
 
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Explains what set operators are and how to use UNION. The full Introduction to Oracle SQL course is available here: https://www.databasestar.com/introduction-to-oracle-sql-course/
Views: 267 Database Star
SQL SERVER UNION QUERY EXAMPLE
 
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https://www.udemy.com/sql-server-fast-track-intro-to-queries/learn/v4/overview This tutorial illustrates how to use a UNION QUERY when you need to merge two data sets into one complete data set. It covers some details that may not occur to the beginner.
Views: 6364 Dave Merton
8. SQL Tutuorial -Telugu (Union,Union all)
 
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Explaining about union and union all
Views: 5909 lakshmi sowbhagya
SQL Tutorial - UNION ALL
 
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This video will teach you how to use UNION ALL, a Set Operator available within SQL Server. UNION ALL allows users to combine multiple sets in to one result set.
Views: 193 BeardedDev
Difference between union intersect and except in sql server
 
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difference between union and union all difference between intersect and union difference between intersect and except in sql server union vs union all sql server union vs intersect sql server intersect vs except In this video we will discuss the difference between union intersect and except in sql server with examples. UNION operator returns all the unique rows from both the left and the right query. UNION ALL included the duplicates as well. INTERSECT operator retrieves the common unique rows from both the left and the right query. EXCEPT operator returns unique rows from the left query that aren’t in the right query’s results. UNION operator returns all the unique rows from both the queries. Notice the duplicates are removed. Select Id, Name, Gender from TableA UNION Select Id, Name, Gender from TableB UNION ALL operator returns all the rows from both the queries, including the duplicates. Select Id, Name, Gender from TableA UNION ALL Select Id, Name, Gender from TableB INTERSECT operator retrieves the common unique rows from both the left and the right query. Notice the duplicates are removed. Select Id, Name, Gender from TableA INTERSECT Select Id, Name, Gender from TableB EXCEPT operator returns unique rows from the left query that aren’t in the right query’s results. Select Id, Name, Gender from TableA EXCEPT Select Id, Name, Gender from TableB If you wnat the rows that are present in Table B but not in Table A, reverse the queries. Select Id, Name, Gender from TableB EXCEPT Select Id, Name, Gender from TableA For all these 3 operators to work the following 2 conditions must be met The number and the order of the columns must be same in both the queries The data types must be same or at least compatible For example, if the number of columns are different, you will get the following error Msg 205, Level 16, State 1, Line 1 All queries combined using a UNION, INTERSECT or EXCEPT operator must have an equal number of expressions in their target lists. Text version of the video http://csharp-video-tutorials.blogspot.com/2015/09/difference-between-union-intersect-and.html Slides http://csharp-video-tutorials.blogspot.com/2015/09/difference-between-union-intersect-and_7.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 39823 kudvenkat
Select statement in sql server - Part 10
 
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In this video we will learn 1. Select specific or all columns 2. Distinct rows 3. Filtering with where clause. 4. Wild Cards in SQL Server 5. Joining multiple conditions using AND and OR operators 6. Sorting rows using order by 7. Selecting top n or top n percentage of rows Text version of the video http://csharp-video-tutorials.blogspot.com/2012/08/select-statement-part-10.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-10-all-about-select.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 357143 kudvenkat
SQL Joins Tutorial for Beginners - Inner Join, Left Join, Right Join, Full Outer Join
 
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Learn how to create SQL Joins. The first 10 minutes teach you the basics. Inner Join, Left Outer Join, Right Outer Join, and Full Outer Join. The second 10 minutes show you are few techniques that will help you as you start building joins. READ THE ORIGINAL ARTICLE WITH THE TABLE SCRIPS http://www.sqltrainingonline.com/sql-joins-tutorial-for-beginners/ YOUTUBE NEWS UPDATES http://www.youtube.com/user/sqltrainingonline VISIT SQLTRAININGONLINE.COM FOR TONS MORE VIDEO NEWS & TIPS http://www.sqltrainingonline.com SUBSCRIBE FOR OTHER SQL TIPS AND NEWS! http://www.youtube.com/subscription_center?add_user=sqltrainingonline SUBSCRIBE TO OUR EMAIL LIST! http://www.sqltrainingonline.com LET'S CONNECT! Facebook: http://facebook.com/SQLTrainingOnline Twitter: http://twitter.com/sql_by_joey Linkedin: http://linkedin.com/in/joeyblue SQLTrainingOnline: http://www.sqltrainingonline.com
Views: 217368 Joey Blue
Part 1   How to find nth highest salary in sql
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-1-how-to-find-nth-highest-salary_17.html This is a very common SQL Server Interview Question. There are several ways of finding the nth highest salary. By the end of this video, we will be able to answer all the following questions as well. How to find nth highest salary in SQL Server using a Sub-Query How to find nth highest salary in SQL Server using a CTE How to find the 2nd, 3rd or 15th highest salary Let's use the following Employees table for this demo Use the following script to create Employees table Create table Employees ( ID int primary key identity, FirstName nvarchar(50), LastName nvarchar(50), Gender nvarchar(50), Salary int ) GO Insert into Employees values ('Ben', 'Hoskins', 'Male', 70000) Insert into Employees values ('Mark', 'Hastings', 'Male', 60000) Insert into Employees values ('Steve', 'Pound', 'Male', 45000) Insert into Employees values ('Ben', 'Hoskins', 'Male', 70000) Insert into Employees values ('Philip', 'Hastings', 'Male', 45000) Insert into Employees values ('Mary', 'Lambeth', 'Female', 30000) Insert into Employees values ('Valarie', 'Vikings', 'Female', 35000) Insert into Employees values ('John', 'Stanmore', 'Male', 80000) GO To find the highest salary it is straight forward. We can simply use the Max() function as shown below. Select Max(Salary) from Employees To get the second highest salary use a sub query along with Max() function as shown below. Select Max(Salary) from Employees where Salary [ (Select Max(Salary) from Employees) To find nth highest salary using Sub-Query SELECT TOP 1 SALARY FROM ( SELECT DISTINCT TOP N SALARY FROM EMPLOYEES ORDER BY SALARY DESC ) RESULT ORDER BY SALARY To find nth highest salary using CTE WITH RESULT AS ( SELECT SALARY, DENSE_RANK() OVER (ORDER BY SALARY DESC) AS DENSERANK FROM EMPLOYEES ) SELECT TOP 1 SALARY FROM RESULT WHERE DENSERANK = N To find 2nd highest salary we can use any of the above queries. Simple replace N with 2. Similarly, to find 3rd highest salary, simple replace N with 3. Please Note: On many of the websites, you may have seen that, the following query can be used to get the nth highest salary. The below query will only work if there are no duplicates. WITH RESULT AS ( SELECT SALARY, ROW_NUMBER() OVER (ORDER BY SALARY DESC) AS ROWNUMBER FROM EMPLOYEES ) SELECT SALARY FROM RESULT WHERE ROWNUMBER = 3
Views: 1004570 kudvenkat
Rank and Dense Rank in SQL Server
 
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rank and dense_rank example difference between rank and dense_rank with example rank vs dense_rank in sql server 2008 sql server difference between rank and dense_rank In this video we will discuss Rank and Dense_Rank functions in SQL Server Rank and Dense_Rank functions Introduced in SQL Server 2005 Returns a rank starting at 1 based on the ordering of rows imposed by the ORDER BY clause ORDER BY clause is required PARTITION BY clause is optional When the data is partitioned, rank is reset to 1 when the partition changes Difference between Rank and Dense_Rank functions Rank function skips ranking(s) if there is a tie where as Dense_Rank will not. For example : If you have 2 rows at rank 1 and you have 5 rows in total. RANK() returns - 1, 1, 3, 4, 5 DENSE_RANK returns - 1, 1, 2, 3, 4 Syntax : RANK() OVER (ORDER BY Col1, Col2, ...) DENSE_RANK() OVER (ORDER BY Col1, Col2, ...) RANK() and DENSE_RANK() functions without PARTITION BY clause : In this example, data is not partitioned, so RANK() function provides a consecutive numbering except when there is a tie. Rank 2 is skipped as there are 2 rows at rank 1. The third row gets rank 3. DENSE_RANK() on the other hand will not skip ranks if there is a tie. The first 2 rows get rank 1. Third row gets rank 2. SELECT Name, Salary, Gender, RANK() OVER (ORDER BY Salary DESC) AS [Rank], DENSE_RANK() OVER (ORDER BY Salary DESC) AS DenseRank FROM Employees RANK() and DENSE_RANK() functions with PARTITION BY clause : Notice when the partition changes from Female to Male Rank is reset to 1 SELECT Name, Salary, Gender, RANK() OVER (PARTITION BY Gender ORDER BY Salary DESC) AS [Rank], DENSE_RANK() OVER (PARTITION BY Gender ORDER BY Salary DESC) AS DenseRank FROM Employees Use case for RANK and DENSE_RANK functions : Both these functions can be used to find Nth highest salary. However, which function to use depends on what you want to do when there is a tie. Let me explain with an example. If there are 2 employees with the FIRST highest salary, there are 2 different business cases 1. If your business case is, not to produce any result for the SECOND highest salary, then use RANK function 2. If your business case is to return the next Salary after the tied rows as the SECOND highest Salary, then use DENSE_RANK function Since we have 2 Employees with the FIRST highest salary. Rank() function will not return any rows for the SECOND highest Salary. WITH Result AS ( SELECT Salary, RANK() OVER (ORDER BY Salary DESC) AS Salary_Rank FROM Employees ) SELECT TOP 1 Salary FROM Result WHERE Salary_Rank = 2 Though we have 2 Employees with the FIRST highest salary. Dense_Rank() function returns, the next Salary after the tied rows as the SECOND highest Salary WITH Result AS ( SELECT Salary, DENSE_RANK() OVER (ORDER BY Salary DESC) AS Salary_Rank FROM Employees ) SELECT TOP 1 Salary FROM Result WHERE Salary_Rank = 2 You can also use RANK and DENSE_RANK functions to find the Nth highest Salary among Male or Female employee groups. The following query finds the 3rd highest salary amount paid among the Female employees group WITH Result AS ( SELECT Salary, Gender, DENSE_RANK() OVER (PARTITION BY Gender ORDER BY Salary DESC) AS Salary_Rank FROM Employees ) SELECT TOP 1 Salary FROM Result WHERE Salary_Rank = 3 AND Gender = 'Female' Text version of the video http://csharp-video-tutorials.blogspot.com/2015/10/rank-and-denserank-in-sql-server.html Slides http://csharp-video-tutorials.blogspot.com/2015/10/rank-and-denserank-in-sql-server_1.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 84336 kudvenkat
Chapter 9 : SQL Set Operators
 
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Set operators are used to join the results of two (or more) SELECT statements.The SET operators available in Oracle 11g are UNION,UNION ALL,INTERSECT,and MINUS. Same number of columns must be selected by all participating SELECT statements.Column names used in the display are taken from the first query. Data types of the column list must be compatible/implicitly convertible by oracle. Oracle will not perform implicit type conversion if corresponding columns in the component queries belong to different data type groups.For example, if a column in the first component query is of data type DATE, and the corresponding column in the second component query is of data type CHAR,Oracle will not perform implicit conversion, but raise ORA-01790 error. Positional ordering must be used to sort the result set. Individual result set ordering is not allowed with Set operators. ORDER BY can appear once at the end of the query. For example, UNION and INTERSECT operators are commutative, i.e. the order of queries is not important; it doesn't change the final result. Performance wise, UNION ALL shows better performance as compared to UNION because resources are not wasted in filtering duplicates and sorting the result set. Set operators can be the part of sub queries. Set operators can't be used in SELECT statements containing TABLE collection expressions. The LONG, BLOB, CLOB, BFILE, VARRAY,or nested table are not permitted for use in Set operators.For update clause is not allowed with the set operators.
Difference between rows and range
 
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range vs rows in sql server difference between rows clause and range clause in sql server range clause vs rows clause in sql server sql server running total query running total example in sql server In this video we will discuss the difference between rows and range in SQL Server. This is continuation to Part 116. Please watch Part 116 from SQL Server tutorial before proceeding. Let us understand the difference with an example. We will use the following Employees table in this demo. SQL Script to create the Employees table Create Table Employees ( Id int primary key, Name nvarchar(50), Salary int ) Go Insert Into Employees Values (1, 'Mark', 1000) Insert Into Employees Values (2, 'John', 2000) Insert Into Employees Values (3, 'Pam', 3000) Insert Into Employees Values (4, 'Sara', 4000) Insert Into Employees Values (5, 'Todd', 5000) Go Calculate the running total of Salary and display it against every employee row The following query calculates the running total. We have not specified an explicit value for ROWS or RANGE clause. SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary) AS RunningTotal FROM Employees So the above query is using the default value which is RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW This means the above query can be re-written using an explicit value for ROWS or RANGE clause as shown below. SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal FROM Employees We can also achieve the same result, by replacing RANGE with ROWS SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal FROM Employees What is the difference between ROWS and RANGE To understand the difference we need some duplicate values for the Salary column in the Employees table. Execute the following UPDATE script to introduce duplicate values in the Salary column Update Employees set Salary = 1000 where Id = 2 Update Employees set Salary = 3000 where Id = 4 Go Now execute the following query. Notice that we get the running total as expected. SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal FROM Employees The following query uses RANGE instead of ROWS SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal FROM Employees Notice we don't get the running total as expected. So, the main difference between ROWS and RANGE is in the way duplicate rows are treated. ROWS treat duplicates as distinct values, where as RANGE treats them as a single entity. All together side by side. The following query shows how running total changes 1. When no value is specified for ROWS or RANGE clause 2. When RANGE clause is used explicitly with it's default value 3. When ROWS clause is used instead of RANGE clause SELECT Name, Salary, SUM(Salary) OVER(ORDER BY Salary) AS [Default], SUM(Salary) OVER(ORDER BY Salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS [Range], SUM(Salary) OVER(ORDER BY Salary ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS [Rows] FROM Employees Text version of the video http://csharp-video-tutorials.blogspot.com/2015/10/difference-between-rows-and-range.html Slides http://csharp-video-tutorials.blogspot.com/2015/10/difference-between-rows-and-range_8.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 37010 kudvenkat
Union, Union All - MySQL
 
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Discussed in detail the standard keywords that are used very commonly to write queries. These are basic examples that can be used for beginners.
Views: 2617 Gattu Guntur
SQL Cơ Bản - Bài 8: Sử dụng toán tử tổ hợp UNION/ UNION ALL, INTERSECT, MINUS
 
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Bài số 8 trong loạt bài về Oracle SQL Fundametal. - Nội dung bám sát chương trình học SQL Fundametal của Oracle. - Cần thiết cho tất cả Database Developer/ Database Adminstrator. - Trang bị kiến thức cho các môn thi: 1Z0-051, 1Z0-061, 1Z0-071, ...
Views: 5726 1Click2beDBA
Oracle Using In , Between and Not تعليم أوراكل
 
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by Mohamed El Desouki - محمد الدسوقى [email protected] Tel :00966 553450836 جامعة سلمان بن عبد العزيز - السعودية - الخرج How to use In , Between and Not. Text Book: Fundamentals of Database Systems, 5th Edition, by Elmasri/Navathe, published by Addison-W oracle create table statement oracle drop table statement oracle constraints database constraints primary key constraint foreign key constraint check constraint null not null constraint unique constraint insert into statement update statement delete statement select statement basic query where clause select where Like '%' Like '_' select where Like select where Between Between , Not Between select where In , Not In
SQL tutorial 49: CASE - Simple Case Expression in Oracle Database (1/2)
 
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Case expression let you perform IF-THEN-ELSE in oracle database. There are two type of case in oracle simple case expression and searched case expression. This SQL Tutorial 49 is about Simple Case Expression. ● What Is Case Expression ● Syntax of Simple Case Expression ● Query 1. Column name of a table as Search expression in CASE ● Query 2. String as Search expression in CASE Celebrating 1000 subscribers. Thanks a lot guys for all your love and support. ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog: http://bit.ly/simple-case-expression ------------------------------------------------------------------------- Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=kb4rc1 -------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the first one to see my videos! -------------------------------------------------------------------------- Amazon Wishlist: http://bit.ly/wishlist-amazon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider https://www.facebook.com/imthebhardwaj http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ http://rebellionrider.tumblr.com/ http://www.pinterest.com/rebellionrider/ You can also Email me at [email protected] Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 40554 Manish Sharma
24. SQL UNION & UNION ALL
 
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In this video we will learn about the 1. Purpose of UNION and UNION ALL 2. Difference between UNION and UNION ALL. Union and Union all Set operator in SQL/Oracle Database with example also the difference between union and union all. Please Subscribe Channel Like, Share and Comment. For more videos follow : https://youtu.be/FM6DCOKuLw0
Views: 144 ProSchool
DISTINCT Clause & UNIQUE Keyword in Oracle | Oracle Tutorials for Beginners
 
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DISTINCT & UNIQUE Keyword in Oracle | Oracle Tutorials for Beginners DISTINCT Keyword in Oracle DISTINCT Clause in Oracle UNIQUE Keyword in Oracle UNIQUE Clause in Oracle Oracle Tutorials for Beginners Oracle Tutorials for Beginners select distinct * sql distinct multiple columns sql distinct count select distinct on one column with multiple columns returned select distinct mysql sql count distinct multiple columns oracle distinct count sql distinct group by sql count distinct two columns select distinct on one column with multiple columns returned select distinct on one column with multiple columns returned oracle sql select unique values from multiple columns select distinct multiple columns mysql select distinct all columns sql count distinct multiple columns group by sql select distinct multiple columns group by select distinct oracle select distinct rows sql select distinct multiple columns select distinct on one column select count distinct select unique mysql how to select unique records in oracle without using distinct sql select distinct values and count of each Oracle Tutorials for Beginners Oracle Tutorials for Beginners Oracle Tutorials for Beginners Oracle Tutorials for Beginners
Views: 832 Oracle PL/SQL World
Part 5   SQL query to find employees hired in last n months
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-5-sql-query-to-find-employees.html This question is asked is many sql server interviews. If you have used DATEDIFF() sql server function then you already know the answer. -- Replace N with number of months Select * FROM Employees Where DATEDIFF(MONTH, HireDate, GETDATE()) Between 1 and N
Views: 187594 kudvenkat
SQL Server Tutorial 11- Union, Union All, Intersect and Except
 
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Union, union all, intersect and except
Views: 364 juniorAdmin
SQL Server except operator
 
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sql except example sql except operator example sql server except example sql server except order by sql server except clause SQL Server except operator In this video we will discuss SQL Server except operator with examples. EXCEPT operator returns unique rows from the left query that aren’t in the right query’s results. Introduced in SQL Server 2005 The number and the order of the columns must be the same in all queries The data types must be same or compatible This is similar to minus operator in oracle Let us understand this with an example. SQL Script to create the tables Create Table TableA ( Id int primary key, Name nvarchar(50), Gender nvarchar(10) ) Go Insert into TableA values (1, 'Mark', 'Male') Insert into TableA values (2, 'Mary', 'Female') Insert into TableA values (3, 'Steve', 'Male') Insert into TableA values (4, 'John', 'Male') Insert into TableA values (5, 'Sara', 'Female') Go Create Table TableB ( Id int primary key, Name nvarchar(50), Gender nvarchar(10) ) Go Insert into TableB values (4, 'John', 'Male') Insert into TableB values (5, 'Sara', 'Female') Insert into TableB values (6, 'Pam', 'Female') Insert into TableB values (7, 'Rebeka', 'Female') Insert into TableB values (8, 'Jordan', 'Male') Go Notice that the following query returns the unique rows from the left query that aren’t in the right query’s results. Select Id, Name, Gender From TableA Except Select Id, Name, Gender From TableB To retrieve all of the rows from Table B that does not exist in Table A, reverse the two queries as shown below. Select Id, Name, Gender From TableB Except Select Id, Name, Gender From TableA You can also use Except operator on a single table. SQL script to create tblEmployees table Create table tblEmployees ( Id int identity primary key, Name nvarchar(100), Gender nvarchar(10), Salary int ) Go Insert into tblEmployees values ('Mark', 'Male', 52000) Insert into tblEmployees values ('Mary', 'Female', 55000) Insert into tblEmployees values ('Steve', 'Male', 45000) Insert into tblEmployees values ('John', 'Male', 40000) Insert into tblEmployees values ('Sara', 'Female', 48000) Insert into tblEmployees values ('Pam', 'Female', 60000) Insert into tblEmployees values ('Tom', 'Male', 58000) Insert into tblEmployees values ('George', 'Male', 65000) Insert into tblEmployees values ('Tina', 'Female', 67000) Insert into tblEmployees values ('Ben', 'Male', 80000) Go Except operator on a single table Select Id, Name, Gender, Salary From tblEmployees Where Salary ]= 50000 Except Select Id, Name, Gender, Salary From tblEmployees Where Salary ]= 60000 Order By clause should be used only once after the right query Select Id, Name, Gender, Salary From tblEmployees Where Salary ]= 50000 Except Select Id, Name, Gender, Salary From tblEmployees Where Salary ]= 60000 order By Name Text version of the video http://csharp-video-tutorials.blogspot.com/2015/09/sql-server-except-operator.html Slides http://csharp-video-tutorials.blogspot.com/2015/09/adsbygoogle-window.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 44215 kudvenkat
Part 8   SQL Query to find department with highest number of employees
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/06/part-8-sql-query-to-find-department.html Scenario asked in the SQL Server Interview Based on the above two tables write a SQL Query to get the name of the Department that has got the maximum number of Employees. To answer this question it will be helpful if you the knowledge of JOINS & GROUP BY in SQL Server. We discusses these in Parts 11 & 12 of SQL Server Tutorial video series. SQL query that retrieves the department name with maximum number of employees SELECT TOP 1 DepartmentName FROM Employees JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID GROUP BY DepartmentName ORDER BY COUNT(*) DESC Scenario asked in the SQL Server Interview Based on the above two tables write a SQL Query to get the name of the Department that has got the maximum number of Employees. To answer this question it will be helpful if you the knowledge of JOINS & GROUP BY in SQL Server. We discusses these in Parts 11 & 12 of SQL Server Tutorial video series. SQL query that retrieves the department name with maximum number of employees SELECT TOP 1 DepartmentName FROM Employees JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID GROUP BY DepartmentName ORDER BY COUNT(*) DESC
Views: 132049 kudvenkat
SQL Server 2017 Tutorial 7 - DISTINCT and UNION
 
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DISTINCT, UNION and UNION ALL in SQL Server 2017. Support YPN on Patreon! http://www.patreon.com/YPN Website and Forum: http://yourprogrammingnetwork.co.uk Join us on Facebook! https://www.facebook.com/pages/Your-Programming-Network/280950122022281 Chat on Discord https://discord.gg/br3ZB3f
SQL tutorial 61: SEQUENCE in Oracle Database By Manish Sharma RebellionRider
 
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This tutorial is all about Sequence In Oracle Database. In this SQL Tutorial you will learn How to create a sequence How to populate a Primary key column (auto increment in Oracle) using Sequence How to drop a sequence ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog : http://bit.ly/sql-sequence-in-oracle-database-rebellionrider-manish-sharma Previous Tutorial ► How To Insert Data into Table using SQL Developer http://youtu.be/YYQCSV6MzTk ► INSERT INTO Command http://youtu.be/uQXgqFtxI_k ► How to copy /Insert data into a table from another table http://youtu.be/m3Ep8tAMqok ------------------------------------------------------------------------- ►►►Help Me In Getting A Job◄◄◄ ►Help Me In Getting A Good Job By Connecting With Me on My LinkedIn and Endorsing My Skills. All My Contact Info is Down Below. You Can Also Refer Me To Your Company Thanks ------------------------------------------------------------------------- Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=kb4rc1 -------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! -------------------------------------------------------------------------- Amazon Wishlist: http://bit.ly/wishlist-amazon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider https://www.facebook.com/imthebhardwaj http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ http://rebellionrider.tumblr.com/ http://www.pinterest.com/rebellionrider/ You can also Email me at for E-mail address please check About section Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 46276 Manish Sharma
UNION ALL Operator in SQL ORACLE mp4
 
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In This Course you will learn how to download oracle and install on mac and window in this course topics will covers as Sql Developer Download , Set up connection in SQL Developer , Create a new user , use sample database , Setting up sample database How to view Data with select statment , selecting indiviual columns Filtering Data with Where in Sql Comparision operators Filtering on Partial values with likes , Filter on data values , using two filters What is Null , Getting Unique Records with DISTINCT , What is IN and NOT in oracle , What is between and not between , All keywords which are used in sql , any keyword , sorting result with order by clause , ordering by Multiple columns ,set operation and union , union all operator , insert operator , Minus oprator , three or more sets at once , what are function in oracle , what is data counting , using count in other ways , Counting Data within groups with Group by Group by having clause , The sum function in sql , the avg function in sql What are table alias , what are column alias , what are joins , inner joins What is left join , gight join , outer join , natural join , cartesian and cross join self join , join many tables , alternative join syntax ,string function , nesting function within functions , number function , data function ,data type and conversion , the case statement what are subquries , single row subquries , multirow subquries , inserting data , inserting from another tables , updating data , Deleting data , Commit and Rollback , truncating data Create a table , alter a table drop a table conclusion
Views: 0 Education
17 MySQL Tutorial for Beginners: Unions - Literals - Full Outer Ioins
 
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A union combines the result sets of two or more SELECT statements into one single result set. To code a union you use the UNION keyword to connect two or more SELECT statements. Note that the column names in the final result set are taken from the first SELECT clause. When you code a union, the result of each SELECT statement must have the same number of columns. If you want to sort the result of a union operation, you can code an ORDER BY clause after the last SELECT statement. In an ORDER BY clause, you must use the column names that are specified in the first SELECT statement. That's because the column names in the final result set are taken from the first SELECT clause. Coding literal values instead of column specifications, could be very useful in UNIONS. You can code literal values in the SELECT clause, to indicate which table each row in the result set came from. You can use the UNION keyword to combine the result sets for a left and a right outer joins. This technique is also known as “full outer join“ . Because MySQL does not provide language for coding a full outer join, you can simulate it by coding an union that combines the result sets for a left outer join and a right outer join. EXERCISES for your SELF-TRAINING: http://golearnfast.com/Quizzes.php?_SelectSmallerGroup_294=0&Lessons_ID=294 SCRIPT FOR THE EXAMPLES: http://www.golearnfast.com/files/lessons_material/lesson_277_1440544998.sql SUBSCRIBE! https://www.youtube.com/channel/UCMEaGDoHU7c9tWyafZ9vC6Q?sub_confirmation=1 FACEBOOK https://www.facebook.com/golearnfast GOOGLE+ https://plus.google.com/u/0/b/101326338689489366802/
Views: 2735 golearnfast
Как работает рекурсия? Иерархические / рекурсивные SQL запросы в базах данных SQLite: WITH RECURSIVE
 
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Помощь проекту: WMR: R288272666982 WMZ: Z293550531456 Яндекс.Деньги: 410011531129223 Рубрика SQLite на сайте: http://zametkinapolyah.ru/zametki-o-mysql/sqlite/ Паблик блога в ВК: https://vk.com/zametkinapolyah Тематическая группа в ВК: https://vk.com/zametki_bd -- Рекурсивные/иерархические SQL запросы в базах данных SQLite: -- WITH RECURSIVE clause. /* Не все любят рекурсивные или как еще говорят иерархические SQL запросы. Потому что не всем и не всегда просто понять рекурсию, поэтому, обычно, рекурсивные запросы применяют либо те, кто рекурсию понимают, либо те, кто не ленится эксперементировать и пробовать и в конце концов тоже начинает понимать рекурсию. Здесь мы попробуем разобраться и с рекурсией и с иерархическими SQL-запросами. SQLite, как и многие другие СУБД - реляционная: база данных состоит из таблиц, таблицы в свою очередь состоят из строк и столбцов, другими словами: данные представлены двумерно. В нашей жизни, так уж получается, что не все объекты удобно описывать двумерной моделью: крупная международная компания с холдингами и филиалами в различных странах, файловая система компьютера, карьерная лестница в компании - эти данные намного удобнее описывать иерархической моделью. Конечно, например, структуру крупной компании можно описать несколькими таблицами, например, таблицы стран: Китай, Россия, США, Англия, Япония. Далее спуститься на уровень ниже и создать таблицы регионов для страны: Москва, Иваново, Новосибирск, Омск. Но такой подход не всегда удобен, поскольку не всегда известна глубина вложенности. В 1999 году международное сообщество решило эту проблему путем добавления в стандарт (SQL-1999) рекурсивных SQL-запросов, хотя компания Oracle это сделала немного раньше (и по Ораклу рекурсивные запросы называются иерархическими). */ http://sqlite.org/lang_with.html /* Общий синтаксис рекурсивных запросов в SQLite выглядит следующим образом: WITH [RECURSIVE] cte-table-name AS (select-stmt); Но это не всё, рекурсивный SQL запрос состоит из двух запросов SELECT, если эта фраза в данном случае уместна: WITH RECURSIVE cte-table-name AS (initial-select UNION [ALL] recursive-select) cte-select; 2 1 cte-table-name 1 2 initial-select (не должен в себя включать ORDER BY, LIMIT, OFFSET) - точка, откуда начинается рекурсия. recursive-select - рекурсивный запрос, который будет вполняться до тех пор, пока условие не будет выполнено, два верхних запроса позволяют создать наполнить нашу импровизированную таблицу данными cte-select - позволяет работать с данными таблицы 1-1000 WITH RECURSIVE table1(col1) AS ( VALUES(1) UNION ALL SELECT col1+1 FROM table1 WHERE col1(знак меньше)1000) SELECT col1 FROM table1; WITH RECURSIVE table1(col1) AS ( SELECT 1 UNION ALL SELECT col1+1 FROM table1 LIMIT 1000 ) SELECT col1 FROM table1; table1 col1 2 3 2 1 table1 1 2 3 -- Создадим таблицу CREATE TABLE org( name TEXT PRIMARY KEY, boss TEXT REFERENCES org ); -- наполним ее данными INSERT INTO org VALUES('Alice',NULL); INSERT INTO org VALUES('Bob','Alice'); INSERT INTO org VALUES('Cindy','Alice'); INSERT INTO org VALUES('Dave','Bob'); INSERT INTO org VALUES('Emma','Bob'); INSERT INTO org VALUES('Fred','Cindy'); INSERT INTO org VALUES('Gail','Cindy'); SELECT * FROM org; -- Для лучшего понимания работы рекурсии и поиска значений -- рекомендую вам погуглить: -- FIFO, поиск в глубину и поиск в ширину 0|Alice 1|Bob 1|Cindy 2|Dave 2|Emma 2|Fred 2|Gail -- поиск в глубину WITH RECURSIVE under_alice(name,level) AS ( VALUES('Alice',0) UNION ALL SELECT org.name, under_alice.level+1 FROM org JOIN under_alice ON org.boss=under_alice.name ORDER BY 2 DESC ) SELECT level, name FROM under_alice; Alice ...Bob ...Cindy ......Dave ......Emma ......Fred ......Gail WITH RECURSIVE under_alice(name,level) AS ( VALUES('Alice',0) UNION ALL SELECT org.name, under_alice.level+1 FROM org JOIN under_alice ON org.boss=under_alice.name ORDER BY 2 DESC ) SELECT substr('..........',1,level*3) || name FROM under_alice;
Getting Unique Records with DISTINCT (Introduction to Oracle SQL)
 
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How to find unique records using the DISTINCT keyword
Views: 203 Database Star