自定义无参函数：
mysql> CREATE FUNCTION NOW_() RETURNS VARCHAR(30) RETURN DATE_FORMAT(NOW(),'%Y年%m月%d日 %H时：%i分：%s秒'); Query OK, 0 rows affected (0.00 sec) mysql> SELECT NOW_(); +-----------------------------------------+ | NOW_() | +-----------------------------------------+ | 2018年05月17日 17时：18分：37秒 | +-----------------------------------------+ 1 row in set (0.00 sec)自定义有参函数：
mysql> CREATE FUNCTION AVG_(num1 SMALLINT UNSIGNED,num2 SMALLINT UNSIGNED) -> RETURNS FLOAT(10,2) UNSIGNED -> RETURN (num1+num2)/2; Query OK, 0 rows affected (0.04 sec) mysql> SELECT AVG_(2,3); +-----------+ | AVG_(2,3) | +-----------+ | 2.50 | +-----------+ 1 row in set (0.02 sec)删除函数：
mysql> DROP FUNCTION AVG_; Query OK, 0 rows affected (0.00 sec)修改终止符：DELIMITER
mysql> DELIMITER // mysql> DESC 名单// +-------+----------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+----------------------+------+-----+---------+----------------+ | id | smallint(5) unsigned | NO | PRI | NULL | auto_increment | | 姓 | varchar(12) | NO | | NULL | | | 名 | varchar(24) | NO | | NULL | | +-------+----------------------+------+-----+---------+----------------+ 3 rows in set (0.00 sec)复合结构函数体：将插入到名单的方法封装成一个函数，返回插入id值
mysql> CREATE FUNCTION add_name(first_name VARCHAR(12),last_name VARCHAR(24)) -> RETURNS SMALLINT UNSIGNED -> BEGIN -> INSERT 名单 VALUES(NULL,first_name,last_name); -> RETURN LAST_INSERT_ID(); -> END// Query OK, 0 rows affected (0.00 sec)使用：
mysql> SELECT add_name('黄','月英')// +--------------------------+ | add_name('黄','月英') | +--------------------------+ | 7 | +--------------------------+ 1 row in set (0.01 sec) mysql> SELECT*FROM 名单// +----+--------+--------+ | id | 姓 | 名 | +----+--------+--------+ | 1 | 张 | 飞 | | 2 | 刘 | 备 | | 3 | 关 | 羽 | | 4 | 诸葛 | 亮 | | 5 | 赵% | 云 | | 6 | 马 | 超 | | 7 | 黄 | 月英 | +----+--------+--------+ 7 rows in set (0.00 sec) mysql> DELIMITER ; mysql>转载于:https://www.cnblogs.com/toly-top/p/9782014.html
