PHP to return custom error messages from MySQL

Hi,

I have a database which has two fields which must contain unique date.

At the moment I am currently using mysql_error() to return the error
message. And this returns "Duplicate entry 'aaa' for key 2" and
Duplicate entry 'bbb' for key 3". I know what each key means but how
can I send a custom error message say field x is already registered on
our system please try again?


Many thanks in advanced.

Iain wrote:
> Hi,
>
> I have a database which has two fields which must contain unique date.
>
> At the moment I am currently using mysql_error() to return the error
> message. And this returns "Duplicate entry 'aaa' for key 2" and
> Duplicate entry 'bbb' for key 3". I know what each key means but how
> can I send a custom error message say field x is already registered on
> our system please try again?
>
>
> Many thanks in advanced.

Rather than just error-handling, you could add the IGNORE keyword to
your INSERT query, i.e.

INSERT IGNORE INTO table (aaa, bbb) VALUES ($valA, $valB)

Then look at mysql_affected_rows(). If it returns zero, the row was not
added, so you could then do something like:

SELECT COUNT(*) FROM table WHERE aaa=$valA

If COUNT(*) is non-zero, it was aaa that was the duplicate key,
otherwise it was bbb.

Not particularly elegant, but IMO more elegant than causing an error and
then substring matching on the error string (the only real alternative I
can see at the moment).

--
Oli