Include a warning message for zero-value date when reading data from a table using date and time functions

12.1.2>CREATE OR REPLACE TABLE t1 (a DATE, b DATE);

Query OK, 0 rows affected (0.103 sec)

12.1.2>

12.1.2>INSERT INTO t1 VALUES ("2003-12-15", "0000-00-00");

Query OK, 1 row affected (0.008 sec)

12.1.2>

12.1.2>SELECT DATEDIFF(a,b) FROM t1;

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

| DATEDIFF(a,b) |

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

|          NULL |

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

1 row in set (0.000 sec)

12.1.2>

12.1.2>SELECT DATEDIFF("2003-12-15", "0000-00-00");

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

| DATEDIFF("2003-12-15", "0000-00-00") |

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

|                                 NULL |

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

1 row in set, 1 warning (0.000 sec)

12.1.2>SHOW WARNINGS;

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

| Level   | Code | Message                                |

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

| Warning | 1292 | Incorrect datetime value: '0000-00-00' |

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

1 row in set (0.000 sec)

12.1.2>