What is the difference between UNION ALL Statement and UNION

 Posted by Chikul on 12/21/2009 | Category: Sql Server Interview questions | Views: 2179

The main difference between UNION ALL statement and UNION is UNION All statement is much faster than UNION.
Reason : Because UNION ALL statement does not look for duplicate rows, but on the other hand UNION statement does look for duplicate rows, whether or not they exist.

Asked In: Many Interviews | Alert Moderator 

Comments or Responses

Login to post response