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Message Posted: Fri, 10 May 2002 @ 13:29:01 GMT

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Subj:   Re: Where clause in insert macro
From:   Geoffrey Rommel

  And I believe you can't have a WHERE clause when you are using the VALUES clause.  

Right. How could you? WHERE examines the values in existing rows of the table, but insert adds a new row. Moreover, when WHERE is specified, some rows may meet the condition and others may not. Single-row insert, however, is unconditional: if you don't want the new row, you just don't perform the insert.

And another thing! A statement that would in effect be "if (some-condition) then insert, else do nothing" would introduce sequential logic into SQL, which generally should be avoided. (Yes, I know, the CASE expression is sequential.) Let's try to keep SQL as relationally pure as we can.


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