Archives of the TeradataForum
Message Posted: Fri, 10 May 2002 @ 13:29:01 GMT
| 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.