mysql_field_flags(result_id, field_position)
This function returns a string containing the flags associated with the specified field (field_position) in the specified result set (result_id). The flags are separated by spaces in the returned string. Possible flags are: not_null, primary_key, unique_key, multiple_key, blob, unsigned, zerofill, binary, enum, auto_increment, and timestamp.
The function name mysql_fieldflags may also be used, but is deprecated.