mysql>  select left('a','ca'); show warnings;

+----------------+

| left('a','ca') |

+----------------+

|                |

+----------------+

1 row in set, 2 warnings (0.00 sec)

+---------+------+-----------------------------------------+

| Level   | Code | Message                                 |

+---------+------+-----------------------------------------+

| Warning | 1292 | Truncated incorrect INTEGER value: 'ca' |

| Warning | 1292 | Truncated incorrect INTEGER value: 'ca' |

+---------+------+-----------------------------------------+

2 rows in set (0.00 sec)