From: "Harald Fuchs" <[EMAIL PROTECTED]>
> In article <[EMAIL PROTECTED]>, > "Jigal van Hemert" <[EMAIL PROTECTED]> writes: > > > Fortunately there is function COALESCE() that will return the first argument > > that is not NULL. In case of NULL values you can use a default value for an > > expression: COALESCE( `col`*2, 14) will produce 14 if `col` is NULL. > > This idiom, albeit terse, is not something you should get used to, > because it precludes index usage. I didn't say you should use it in a WHERE clause or other condition on large tables! ;-P I used a lot of COALESCE's to calculate some kind of score for each selected record and that was pretty fast. In this particular case I could find NULL values, but the score should still be a number. The COALESCE function came in handy to turn NULL values in some kind of default. But you're right when it comes to fast queries one should only compare columns to other columns or constants (these could be calculated constants). Regards, Jigal. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
