How to combine results from two or more queries.

Problem: How to combine results from two or more queries.

Solution: UNION, Starting SQL Server 2008 or higher.

Combines the results of two or more queries into a single result set that includes all the rows that belong to all queries in the union. The UNION operation is different from using joins that combine columns from two tables.

The following are basic rules for combining the result sets of two queries by using UNION:

·         The number and the order of the columns must be the same in all queries.

·         The data types must be compatible.

Example:

In this article I am going to show you how Union can be used and a few examples.

I Have an employee table and I am filter the table by filtering on employee type and this two give two separate results.

select  * from dbo.employees where employeetype='tester'

select * from dbo.employees where employeetype='developer'

I am going to combine these two results into a sing result using UNION.

select * from dbo.employees where employeetype='tester'

UNION

select * from dbo.employees where employeetype='developer'

OUTPUT: