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Archives of the TeradataForum
Message Posted: Fri, 10 May 2002 @ 13:29:01 GMT
| Subj: | | Re: Where clause in insert macro |
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| 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.
--wgr
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