I have a table that looks like:

username - var
ignore_user - var, default NULL
ignore_id - int unsigned, default NULL

I have a UNIQUE index on username + ignore_user, and another on username + ignore_id.

The query that I'm using is (in PHP):

$hide_query = sprintf(<<<EOF
INSERT IGNORE INTO ignorelist VALUES('%s', '%s', '%s')
EOF
 ,
 mysqli_real_escape_string($dbh, $user),
 mysqli_real_escape_string($dbh, $hide_username),
 mysqli_real_escape_string($dbh, $hide_id));

In the script, I will either have a value for $hide_username OR $hide_id, but never both.

The problem I'm having is when there's a value for $hide_username and none for $hide_id, it sets a value of 0 instead of NULL. But then when I set another row with the same $user and a different value for $hide_username, it doesn't write because it's matching the username + ignore_id index.

Can you guys and gals suggest a way to modify either the table or the script so that the UNIQUE doesn't match like that? My only idea was to change it from INT to VAR, but is that the best way?