mysql>
mysql> CREATE TABLE date_val
-> (
-> d DATE
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql> INSERT INTO date_val (d) VALUES('1864-02-28');
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO date_val (d) VALUES('1900-01-15');
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO date_val (d) VALUES('1987-03-05');
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO date_val (d) VALUES('1999-12-31');
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO date_val (d) VALUES('2000-06-04');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql>
mysql> SELECT d, DATE_SUB(d,INTERVAL DAYOFMONTH(d)-1 DAY) AS '1st of month' FROM date_val;
+------------+--------------+
| d | 1st of month |
+------------+--------------+
| 1864-02-28 | 1864-02-01 |
| 1900-01-15 | 1900-01-01 |
| 1987-03-05 | 1987-03-01 |
| 1999-12-31 | 1999-12-01 |
| 2000-06-04 | 2000-06-01 |
+------------+--------------+
5 rows in set (0.00 sec)
mysql>
mysql> drop table date_val;
Query OK, 0 rows affected (0.00 sec)