This is kind of similar to this question:
PHP MySQL INSERT fails due to unique constraint
but I have a different twist. Let's say I have a table with only one column. The column's name is "title" and it has a unique constraint placed on it.
First I insert a row where title = "something". The next time I try to insert "something" it will fail due to a unique key constraint (which is good). What I'd like to do is allow it to fail, and check the error code provided by mysql to ensure it failed due to a unique key constraint. (i.e. let the database handle the uniqueness, and I just handle the error code and tell the user that title already exists when the result comes back).
Is there a way to do this?
http://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
http://php.net/manual/en/function.mysql-errno.php
I've had to do this in the past, and it's not fun:
if( mysql_errno() == 1062) {
// Duplicate key
} else {
// ZOMGFAILURE
}
A note on programming style (Credits to jensgram from this answer)
You should always seek to avoid the use of magic numbers. Instead, you could assign the known error code (1062
) to a constant (e.g. MYSQL_CODE_DUPLICATE_KEY
). This will make your code easier to maintain as the condition in the if
statement is still readable in a few months when the meaning of 1062
has faded from memory :)