SQL UNION Operator

what is use of union and union all Operator in sqlserver.
Last updated:11/3/2015 10:12:30 PM

1 Answers

Anonymous User
Anonymous User

The UNION operator is used to combine the result-set of two or more SELECT statements.

Notice that each SELECT statement within the UNION must have the same number of columns. The columns must also have similar data types. Also, the columns in each SELECT statement must be in the same order.

SQL UNION Syntax

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

Note: The UNION operator selects only distinct values by default.

SQL UNION ALL Syntax

SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;

Note : The UNION operator selects All (duplicate values also) values by default.

For Exp:

Union

SELECT City FROM Customer

UNION

SELECT City FROM Supplier

ORDER BY City

Result :

  

 


 

Result:

 

 

 Union All

SELECT City FROM Customer

UNION
SELECT City FROM Supplier
ORDER BY City

 

Answer