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

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)