Posted by --CELKO-- on 10/02/31 11:51

>> The first table (a) has a list of all my clients. The second table (b) contains all of the clients who have placed orders. <<

The quick answer is to use a LEFT OUTER JOIN or an EXISTS() predicate.


The right answer is to ask why you consider these clients to be
logically diffferent entities. It sounds like what you need is one
table with a status code of some kind to tell you when you have a
client who placed an order versus one who has not (and who returns
orders, etc.).

Why persist redundant data in physical storage? This is called
"attribute splitting" -- you are converting an attribute into a table.

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