mysql实例 日期计算的存储过程

在mysql中，通过存储过程对日期进行计算的例子。

代码如下：

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc() //创建存储过程 日期计算
    -> BEGIN
    ->
    ->   DECLARE TwentyYearsAgoToday DATE;
    ->   DECLARE mystring VARCHAR(250);
    ->
    ->   SET TwentyYearsAgoToday=DATE_SUB(curdate(), interval 20 year);
    ->
    ->   SET mystring=CONCAT('It was ',TwentyYearsAgoToday,' ...');
    ->
    ->   SELECT mystring;
    ->
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql>
mysql> call myProc(); //调用存储过程
+-----------------------+
| 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; //删除存储过程
Query OK, 0 rows affected (0.00 sec)