• create procedure用来创建存储过程，create function用来创建函数
• 函数与存储过程最大的区别就是函数调用有返回值，调用存储过程用call语句，而调用函数就直接引用函数名+参数即可
• Definer和sql security子句指定安全环境
• Definder是MySQL的特殊的访问控制手段，当数据库当前没有这个用户权限时，执行存储过程可能会报错
• sql secuirty的值决定了调用存储过程的方式，取值 ：definer（默认）或者invoker definer:在执行存储过程前验证definer对应的用户如：cdq@127.0.0.1是否存在，以及是否具有执行存储过程的权限，若没有则报错invoker:在执行存储过程时判断inovker即调用该存储过程的用户是否有相应权限，若没有则报错
• IN,OUT,INOUT三个参数前的关键词只适用于存储过程，对函数而言所有的参数默认都是输入参数
• IN输入参数用于把数值传入到存储过程中；OUT输出参数将数值传递到调用者，初始值是NULL；INOUT输入输出参数把数据传入到存储过程，在存储过程中修改之后再传递到调用者
• Delimiter命令是改变语句的结束符，MySQL默认的结束符为;号，由于procedure和function中的;号并不代表创建的结束，所以要替换成另外的结束符以便表示创建的结束
• Rontine_body子句可以包含一个简单的SQL语句，也可以包含多个SQL语句，通过begin…end将这多个SQL语句包含在一起
• MySQL存储过程和函数中也可以包含类似create和drop等DDL语句
• Comment子句用来写入对存储过程和函数的注释
• Language子句用来表示此存储过程和函数的创建语言
• 存储过程和函数被标注为deterministic表明当输入相同的参数是会返回相同的结果，反之如果是not deterministic则表示相同参数不会是相同结果，默认是not deterministic
• 相关属性短语只有咨询含义，并不是强制性的约束
• Contains sql表明此存储过程或函数不包含读或者写数据的语句，这是默认属性
• NO SQL表示此存储过程或函数不包含SQL语句
• Reads sql data表示此存储过程包含诸如select的查询数据的语句，但不包含插入或删除数据的语句
• Modifies sql data表示此存储过程包含插入或删除数据的语句
• Drop procedure/function语句用来删除指定名称的存储过程或函数
• If exists关键词用来避免在删除一个本身不存在的存储过程或函数时，MySQL返回错误
• Begin…end语句通常出现在存储过程、函数和触发器中，其中可以包含一个或多个语句，每个语句用;号隔开
创建存储过程：
/*在创建之前如果存在同名存储过程，则删除*/ drop PROCEDURE if EXISTS create_student; /*修改分分隔符为;;*/ delimiter ;; create PROCEDURE create_student (OUT new_stuid INT,IN new_name VARCHAR(10),IN birth date,IN addr VARCHAR(50),IN gender VARCHAR(10),IN sub_jct VARCHAR(10)) BEGIN /*为new_stuid声明变量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入数据到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); END;; delimiter ;
调用存储过程：
mysql> call create_student(@new_stuid,"王超人",'1999-03-04','广东深圳','男生','计算机'); Query OK, 1 row affected (0.08 sec) mysql> select @new_stuid; +------------+ | @new_stuid | +------------+ | NULL | +------------+ 1 row in set (0.00 sec) mysql> select * from tb_student2; +-------+--------------+--------+------------+--------------+--------+ | stuid | stuname | stusex | stubirth | stuaddr | collid | +-------+--------------+--------+------------+--------------+--------+ | 1001 | 张三 | 0 | 1990-03-04 | ABCabc | 1 | | 1002 | 季墨 | 0 | 1992-02-02 | 湖南长沙 | 1 | | 1033 | 王语嫣 | 1 | 1989-12-03 | 四川成都 | 1 | | 1378 | 纪嫣然 | 1 | 1995-08-12 | 四川绵阳 | 1 | | 1572 | 张子文 | 0 | 1993-07-19 | 陕西咸阳 | 1 | | 1954 | 张学友 | 0 | 1994-09-20 | 福建莆田 | 1 | | 2035 | 东方不败 | NULL | 1988-06-30 | NULL | 2 | | 3011 | 金大牙 | 0 | 1985-12-12 | 福建莆田 | 3 | | 3755 | 猪脚 | 0 | 1993-01-25 | NULL | 3 | | 3923 | 杨不悔 | 1 | 1985-04-17 | 四川成都 | 3 | | 3924 | 王超人 | 2 | 1999-03-04 | 广东深圳 | 2 | | 3925 | 王超人2 | 2 | 1999-03-04 | 广东深圳 | 2 | +-------+--------------+--------+------------+--------------+--------+ 12 rows in set (0.00 sec) mysql>
把上面的例子改造成函数
/*在创建之前如果存在同名函数，则删除*/ drop FUNCTION if EXISTS create_student_function; /*修改分分隔符为;;*/ delimiter ;; create FUNCTION create_student_function (new_name VARCHAR(10),birth date,addr VARCHAR(50),gender VARCHAR(10),sub_jct VARCHAR(10)) RETURNS INT BEGIN /*为new_stuid声明变量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入数据到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); RETURN new_stuid; END;; delimiter ;
调用函数
mysql> select create_student("王超人",'1999-03-04','广东深圳','男生','计算机'); ERROR 1305 (42000): FUNCTION school.create_student does not exist mysql> select create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机') | +---------------------------------------------------------------------------------------+ | 3926 | +---------------------------------------------------------------------------------------+ 1 row in set, 8 warnings (0.09 sec) mysql> select create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机') | +---------------------------------------------------------------------------------------+ | 3927 | +---------------------------------------------------------------------------------------+ 1 row in set (0.06 sec) mysql> select create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','广东深圳','男生','计算机') | +---------------------------------------------------------------------------------------+ | 3928 | +---------------------------------------------------------------------------------------+ 1 row in set (0.05 sec) mysql>
查看所有存储例程：
mysql> show procedure status like '%create_student%'; +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation | +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | school | create_student | PROCEDURE | root@% | 2020-08-08 23:08:22 | 2020-08-08 23:08:22 | DEFINER | | utf8 | utf8_general_ci | utf8_bin | +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql> show function status like '%create%'; +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation | +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | school | create_student_function | FUNCTION | root@% | 2020-08-09 16:47:51 | 2020-08-09 16:47:51 | DEFINER | | utf8 | utf8_general_ci | utf8_bin | +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ 1 row in set (0.01 sec) mysql>
查看存储例程创建语句
mysql> show create procedure create_student; +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | Procedure | sql_mode | Create Procedure | character_set_client | collation_connection | Database Collation | +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | create_student | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`%` PROCEDURE `create_student`(OUT new_stuid INT,IN new_name VARCHAR(10),IN birth date,IN addr VARCHAR(50),IN gender VARCHAR(10),IN sub_jct VARCHAR(10)) BEGIN /*为new_stuid声明变量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入数据到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); END | utf8 | utf8_general_ci | utf8_bin | +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql> show create function create_student_function; +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | Function | sql_mode | Create Function | character_set_client | collation_connection | Database Collation | +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | create_student_function | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`%` FUNCTION `create_student_function`(new_name VARCHAR(10),birth date,addr VARCHAR(50),gender VARCHAR(10),sub_jct VARCHAR(10)) RETURNS int(11) BEGIN /*为new_stuid声明变量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入数据到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); RETURN new_stuid; END | utf8 | utf8_general_ci | utf8_bin | +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql>
存储例程删除
mysql> drop function create_student_function; Query OK, 0 rows affected (0.02 sec) mysql> show function status like '%create%'; Empty set (0.00 sec) mysql> drop procedure create_student; Query OK, 0 rows affected (0.03 sec) mysql> show procedure status like '%create_student%'; Empty set (0.00 sec) mysql>
• 标签label可以加在begin…end语句以及loop, repeat和while语句
• 语句中通过iterate和leave来控制流程，iterate表示返回指定标签位置，leave表示跳出标签
使用label标签
drop PROCEDURE if EXISTS test_procedure; delimiter // CREATE procedure test_procedure(in p1 int,out p2 int) BEGIN label1:LOOP set p1 = p1 + 1; if p1 < 10 then ITERATE label1;END if; LEAVE label1; END LOOP label1; set p2=p1; END; //
调试下：
mysql> call test_procedure(5,@p2); Query OK, 0 rows affected (0.00 sec) mysql> select @p2; +------+ | @p2 | +------+ | 10 | +------+ 1 row in set (0.00 sec) mysql>
Declare语句
• Declare语句通常用来声明本地变量、游标、条件或者handler
• Declare语句只允许出现在begin … end语句中而且必须出现在第一行
• Declare的顺序也有要求，通常是先声明本地变量，再是游标，然后是条件和handler
存储过程中的变量
• 本地变量可以通过declare语句进行声明
• 声明后的变量可以通过select … into var_list进行赋值，或者通过set语句赋值，或者通过定义游标并使用fetch … into var_list赋值
• 通过declare声明变量方法
• 使用default指定变量的默认值，如果没有指定默认值则初始值为NULL
• Type指明该变量的数据类型
• 声明的变量作用范围为被声明的begin … end语句块之间
• 声明的变量和被引用的数据表中的字段名要区分开来
变量声明在上面的例子里用到了，游标后面学到再写。