Posted by Gordon Burditt on 06/14/05 16:20

>> The database can do this by implementing a unique constraint on the column
>> user_name. After issuing the INSERT, (or any SQL command), check for an
>> error, and report it. This then solves your general problem of enforcing
>> data integrity and reporting errors.
>checking for the SQL error is not a good idea, actually.
>Well known programing prupose to use select before insert.

This has the well-known problem that you may find the name not
in use, insert it, and find the name has been taken before you
got to it - unless you've gotten a lock first.

Gordon L. Burditt

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