Posted by bbla32 on 02/19/07 21:12

> Use a CASE expression. To adapt your second example:
>
> SELECT col1, col2, col3,
> CASE WHEN (condition1) THEN 'Y' ELSE 'N' END AS WasCondition1,
> CASE WHEN (condition2) THEN 'Y' ELSE 'N' END AS WasCondition2
> WHERE (condition1) OR (condition2) ;


Well, then each condition will be checked twice -- performance
decreases (the conditions use subqueries)?


> Always avoid using SELECT *.

Why?

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