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frank43
Starting Member
1 Post |
 Posted - 2014-06-30 : 10:04:50
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| Hi. Does it matter how the code is ordered in a simple CASE statement e.g. does it matter if X comes after Y or 1 comes after 2?CASE X WHEN 1 THEN... WHEN 2 THEN...CASE Y WHEN 1 THEN... WHEN 2 THEN...END;thanks |
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James K
Master Smack Fu Yak Hacker
3873 Posts |
Posted - 2014-06-30 : 10:31:15
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quote:
Originally posted by frank43
Hi. Does it matter how the code is ordered in a simple CASE statement e.g. does it matter if X comes after Y or 1 comes after 2?CASE X WHEN 1 THEN... WHEN 2 THEN...CASE Y WHEN 1 THEN... WHEN 2 THEN...END;thanks
The way you have written the case expression is incorrect. It is eitherCASE X WHEN 1 THEN ... WHEN 2 THEN ...END orCASE WHEN X = 1 THEN ... WHEN X = 2 THEN ...END The order in which the logical comparisons are made matters. Once it finds a comparison that is true, then it won't evaluate the remaining expressions. For example this will print A and not B:declare @x INT = 1;SELECT CASE WHEN @x = 1 THEN 'A' WHEN @x = 1 THEN 'B'END |
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CASE execution order