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case statement

Author

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tpiazza55
Posting Yak Master

162 Posts

Posted - 2012-01-16 : 19:23:38

i have a table

tranid detailkey detailvalue
1 key1 value1
1 key2 value2

on a update statement i only want to update 1 detailvalue with a case statement

CASE
WHEN detailkey = 'key1' THEN newvalue1
end

this updates key1 value but makes key2 value null

how do you use a case to update the one you want and not touch the other values?

sunitabeck
Master Smack Fu Yak Hacker

5155 Posts

Posted - 2012-01-16 : 19:31:54

Use a where clause like this:

UPDATE yourTable SET
	detailValue = newValue
WHERE
	detailkey = 'key1';

If you must use a case expression, do it like this, where you explicitly tell SQL to leave detailValue alone (i.e., set it to itself) if detailkey is not key1

UPDATE yourTable SET
detailValue = 
	CASE 
		WHEN detailkey = 'key1' THEN newvalue1
		ELSE detailValue
	END

tpiazza55
Posting Yak Master

162 Posts

Posted - 2012-01-17 : 12:02:35

thanks

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