SQL Server data set intersection, and, and differential set operations (INTERSECT,UNION,EXCEPT)

Source: Internet
Author: User

SQL Server uses intersect,union,except and three keywords to correspond to three sets of intersection, and, and difference.

Their correspondence can refer to the following illustration

Test Example:

Construct A, a, two data set

A:1,2,3,4B:1,2,5   withA as  (SELECT '1'TNOUNION  All SELECT  '2' UNION  All SELECT  '3' UNION  All SELECT  '4'), B as(SELECT '1'TNOUNION  All SELECT  '2' UNION  All SELECT  '5')

Query Example:

1 Union collection and filtering of duplicate data
-- 1 Union collection and filtering of duplicate data   -- results show: 1,2,3,4,5   SELECT *  from A   UNION     SELECT *  from B  
2 Union All collection does not filter duplicate data
-- 2 Union All collection does not filter duplicate data   -- results show: 1,2,3,4,1,2,5   SELECT *  from A   UNION   All  SELECT *  from B  
3 Intersect intersection (data in two tables)
-- 3 Intersect intersection   -- The results show that   SELECT *  from A   Intersect    SELECT *  from B  
4 except set (Take a A-B record)
-- 4 except difference set   -- results show: 3,4   SELECT *  from A   except    SELECT *  from B  

SQL Server data set intersection, and, and differential set operations (INTERSECT,UNION,EXCEPT)

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