MS SQL Server Interview Question:

How To Use UNION to Merge Outputs from Two Queries Together in MS SQL Server?

Submitted by: Administrator

If you have two queries that returns the same row fields, you can merge their outputs together with the UNION operator. The following tutorial exercise shows you how to use the UNION operator:

SELECT * FROM ggl_links WHERE tag = 'DBA'
GO
<pre>
id url notes counts created tag
102 globalguideline.com NULL 972 2007-05-19 DBA
104 www.mysql.com 390 2006-01-01 DBA
105 www.oracle.com 960 2005-01-01 DBA
</pre>
SELECT * FROM ggl_links WHERE tag = 'DEV'
GO
<pre>
id url notes counts created tag
101 globalguideline.com/html NULL 120 2006-04-30 DEV
106 www.php.net 439 2004-01-01 DEV
</pre>
SELECT * FROM ggl_links WHERE tag = 'DBA'
UNION
SELECT * FROM ggl_links WHERE tag = 'DEV'
GO
<pre>
id url notes counts created tag
102 globalguideline.com NULL 972 2007-05-19 DBA
104 www.mysql.com 390 2006-01-01 DBA
105 www.oracle.com 960 2005-01-01 DBA
101 globalguideline.com/html NULL 120 2006-04-30 DEV
106 www.php.net 439 2004-01-01 DEV
</pre>
Submitted by: Administrator