MySQL Tutorial/Procedure Function/DATE

Date calculation in a procedure

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
    -> BEGIN
    ->
    ->   DECLARE TwentyYearsAgoToday DATE;
    ->   DECLARE mystring VARCHAR(250);
    ->
    ->   SET TwentyYearsAgoToday=DATE_SUB(curdate(), interval 20 year);
    ->
    ->   SET mystring=CONCAT("It was ",TwentyYearsAgoToday," ...");
    ->
    ->   SELECT mystring;
    ->
    -> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> call myProc();
+-----------------------+
| mystring              |
+-----------------------+
| It was 1987-07-23 ... |
+-----------------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.02 sec)
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>

DATE DEFAULT "1999-12-31"

mysql>
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
    -> BEGIN
    ->      DECLARE l_date      DATE DEFAULT "1999-12-31";
    ->
    ->     select l_date;
    -> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> call myProc();
+------------+
| l_date     |
+------------+
| 1999-12-31 |
+------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>

DATE type variable

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
    -> BEGIN
    ->     DECLARE my_dob         DATE
    ->             DEFAULT "1960-06-21";         /* My Birthday */
    ->
    ->     select my_dob;
    -> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> call myProc();
+------------+
| my_dob     |
+------------+
| 1960-06-21 |
+------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql>