From: Joe Pluta

SELECT, t1.type, COALESCE(t2.value, t1.value)
FROM t1 LEFT OUTER JOIN t2 ON = and t1.type = t2.type

That ought to do the trick. Basically, if there is a row in T2, t2.value
will be used. Otherwise, t2.value will be NULL and t1.value will be used.

Nothing against Michael's UNION technique, either, this technique just seems
a little more straightforward to me. But that's the thing about SQL; there
are often several ways to do the same thing, and the performance of each
technique may be influenced by the data in the files.


As an Amazon Associate we earn from qualifying purchases.

This thread ...


Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2021 by and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.