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Using Old Values to Define New Values in UPDATE Statements in SQL Server
How to use old values to define new values in UPDATE statements in SQL Server?
✍: FYIcenter.com
If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by column names in the expressions. The tutorial exercise below shows you a good example:
SELECT * FROM fyi_links WHERE id >= 500 GO id url notes counts created 601 moc.retneciyf.ved Wrong 9 2006-04-30 602 moc.retneciyf.abd Wrong 9 2007-05-21 603 moc.retneciyf.aqs Wrong 9 2007-05-23 UPDATE fyi_links SET id = id+200, counts = id*2 WHERE id >= 500 GO (3 row(s) affected) SELECT * FROM fyi_links WHERE id >= 500 GO id url notes counts created 801 moc.retneciyf.ved Wrong 1202 2006-04-30 802 moc.retneciyf.abd Wrong 1204 2007-05-19 803 moc.retneciyf.aqs Wrong 1206 2007-05-19
This statement increased values in the id column by 200. It also updated the counts column with the newly increased id value.
⇒ Importance of Column Order in the SET Clause in Update Statements in SQL Server
⇐ Updating Multiple Rows with One UPDATE Statement in SQL Server
2016-11-02, 1610🔥, 0💬
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