Question

As an example, when inserting a record into a table with a unique index, is it best to test first? e.g.,

$mysqli->query('SELECT email FROM tblUser WHERE email = '[e-mail]'); 

then make sure 0 rows are returned, then do the insert?

$mysqli->query('INSERT INTO tblUser ...'); 

Or is it better to just skip the test and handle the error in the event there’s a duplicate entry?

THANKS!

Answer 1

It’s better to insert and handle any duplicate key errors.

The reason is that if you test first, some other client can still insert the value in the brief moment between your test and your insert. So you’d need to handle errors anyway.