Microsoft KB Archive/175955

= INF: How to Write a Variance Query in SQL Server =

Article ID: 175955

Article Last Modified on 3/14/2005

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APPLIES TO


 * Microsoft SQL Server 6.0 Standard Edition
 * Microsoft SQL Server 6.5 Standard Edition
 * Microsoft SQL Server 7.0 Standard Edition
 * Microsoft SQL Server 2000 Standard Edition

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This article was previously published under Q175955



When you need to make a comparison between a value and the average for that value in the same category, you can execute a variance query. For example, you may want to use a variance query when you want to compare the salary of an employee against the salary of other employees who hold the same title, or when you want a comparison between the price of a book and the price of all the other books of the same category.

To continue the book example, you can execute the query below in the pubs database. Note that this is a correlated subquery, so it will take a while to run against a very large table.

  select

title, price, variance = price - (select avg(price) from titles t2 where t2.type = t1.type)

  from titles t1

Additional query words: sub variant

Keywords: kbhowto kbusage KB175955

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