PHP MySQL Error Log Function

What are your thoughts of using the following function to log mysql errors?

<?php
function sql_query($query)
{
  $q = mysql_query($query);
  if(!$q)
  {
    mysql_query('INSERT INTO mysql_errors (error_query, error_about) VALU开发者_如何学PythonES ('.
    $query.', '.mysql_error().' )');
  }
  return $q;
}
?>

Do you find it useful? How can it be improved?

Should be:

mysql_query("INSERT INTO mysql_errors (error_query, error_about, error_date) VALUES ('".
    mysql_real_escape_string($query)."', '".mysql_real_escape_string(mysql_error())."',NOW())");

I added a date field and sanitised input. There needs to be a way to differentiate new and old errors and a date field does that.

I could use this, if I found a way to induce the right error, to do an SQL injection.

Why not just use MySQL's native error log? Is there some reason to stuff them back into the DB?

It looks like you've not sanitized input, what if $query contains '? It would cause another SQL error.

Provided, of course, you already have your database connections open and do not need to open them here the function would work as expected as long as you have single quotes around the values in the second query. On a related note, is the mysql_error log not sufficient?