[eluser]Bacteria Man[/eluser]
I ran into one of those subtle gotchas that makes perfect sense once the reason for it is identified.
I have a query string which uses a single binding:
$sql = "SELECT DISTINCT(rp.permissions) FROM role r INNER JOIN role_permissions rp ON rp.role_id = r.role_id WHERE r.role_id IN (?)";
The query call looks like this:
$query = $this->db->query($sql, array('roles' => $roles));
...where $roles equals "2,3" (i.e. a comma delimited string with numeric values)
The problem is that CI (and properly so) escapes the string which produces:
SELECT DISTINCT(rp.permissions) FROM role r INNER JOIN role_permissions rp ON rp.role_id = r.role_id WHERE r.role_id IN ('2,3')
As a result MySQL interprets only the first value and drops any subsequent ones.
The obvious solution is to include the $roles variable inline as
$sql = "SELECT DISTINCT(rp.permissions) FROM role r INNER JOIN role_permissions rp ON rp.role_id = r.role_id WHERE r.role_id IN ($roles)";
Using a fixed number of question marks wasn't practical because the number of comma-delimited values can vary from query to query.
This is ordinarily not a good idea, but in this case the risk is minimal because there's no user-inputted data to contend with.
Perhaps this will save someone a little time.