Mysql Storage Programs（存储过程）简笔记
1、什么是存储过程
mysql> delimiter ; mysql> create procedure proc1(out s int) -> begin -> select count(*) into s from mysql.user; -> end -> // mysql> delimiter ; mysql> call proc1(@s); mysql> select @s;
2、创建存储过程
create procedure([[in] |out |inout])
2.1、in values
mysql> delimiter; mysql> create procedure pin(in p_in int) -> begin -> select p_in; -> set p_in=2; -> select p_in; -> end -> // mysql> delimiter ; mysql> set @p_in=1; mysql> call pin(@p_in); mysql> select @p_in;
2.2、out values
example 1:
mysql> delimiter; mysql> create procedure pout(out p_out int) -> begin -> select p_out; -> set p_out=2; -> select p_out; -> end -> // mysql> delimiter ; mysql> set @p_out=1; mysql> call pout(@p_out); mysql> select @p_out
example 2:
mysql> delimiter; mysql> create procedure pinout(inout p_out int) -> begin -> select p_inout; -> set p_inout=2; -> select p_inout; -> end -> // mysql> delimiter ; mysql> set @p_inout=1; mysql> select @p_inout mysql> call pinout(@p_inout); mysql> select @p_inout
2.3、null values
mysql> delimiter; mysql> create definer=`root`@`localhost` procedure `test1`(n1 int) -> begin; -> set @x=0; -> repeat set @x=@x+1; -> insert into world.t3 values (@x); -> until @x>n1 -> end pepeat -> end; -> // mysql> delimiter ; mysql> call test1(10) mysql> select @p_inout
2、循环插入语句
mysql> show create tables t3\G; mysql> delimiter // mysql> create procedure t3(n1 int) -> begin -> set @x=0; -> repeat set @x=@x+1; -> insert int t3 values (@x); -> until @x>n1 -> end; -> // mysql> delimiter ; mysql> call t3(10); mysql> select * from t3;
3、变量定义
declare variable_name [,variable_name...] datatype [default value];
datatype:int,float,date,varchar(length)
decalare l_int int unsigned default 4000000; decalare l_numeric number(8,2) default 9.95; decalare l_datetime datetime default '1999-12-31 23:59:59'; decalare l_varchar varchar(255) default 'This will not be padded';
4、变量赋值
set 变量名 = 表达式值 [,variable_name = expression ...]
mysql> create procedure p1() set @last_procedure ='p1';
mysql> create procedure p2() set selcet coucat('Last procedure was',@last_procedure);
mysql> call p1();
mysql> call p2();
5、变量的作用域
6、注解
--
/*...*/
7、结构化
7.1、if
mysql > delimiter // mysql > create procedure proc2(in p1 int) --> begin --> declare var int; --> set var=p1+1; --> if var=1 then insert into t values(11); --> end if; --> if var=2 then insert into t values(22); --> else insert into t varlues(33); --> end if; --> end; --> // mysql > delimiter ;
7.2、case
mysql > delimiter // mysql > create procedure proc3(in p1 int) --> begin --> declare var int; --> set var=p1+1; --> case var --> when 1 then insert into t values(17); --> when 2 then insert into t values(18); --> else insert into t values(19); --> end case; --> end; --> // mysql > delimiter ;
7.3、while
mysql > delimiter // mysql > create procedure proc4(in p1 int) --> begin --> declare var int; --> set var=0; --> while var<6 do --> insert into t values(var); --> set var=var+1 --> end while; --> end; --> // mysql > delimiter ;
7.4、repeat
mysql > delimiter // mysql > create procedure proc5(in p1 int) --> begin --> declare v int; --> set v=0; --> repeat --> insert into t values(v); --> set v=v+1; --> until v>=5 --> end repeat; --> end; --> // mysql > delimiter ;
7.5、loop
mysql > delimiter // mysql > create procedure proc6(in p1 int) --> begin --> declare v int; --> set v=0; --> loop_lable:loop --> insert into t values(v); --> set v=v+1; --> if v >=5 then --> leave loop_lable; --> end if; --> end loop; --> end; --> // mysql > delimiter ;
7.6、iterate
mysql > delimiter // mysql > create procedure proc7() --> begin --> declare v int default 0; --> loop_lable:loop --> set v=v+1; --> if v<10 then insert loop_lable; --> elseif v>20 then leave loop_lable; --> else select 'v is between 10 and 20'; --> end if; --> end loop loop_lable; --> end; --> // mysql > delimiter ;
8、查看存储过程状态
mysql > show procedure status like 'p%'\G; mysql > select * from information_schema.Routines -> where routine_name = 'p1' -> and ->routing_type='procedure'\G;
9、查看存储过程内容
mysql > show create procedure p2\G;
10、修改存储过程
alter procedure proc_name [characteristic ...]
characteristic:
comment 'sting'
| language sql
| {contains sql | no sql | reads sql data | modifies sql data}
| sql security { definer | invoker}
11、删除存储过程
mysql > drop procedure p2;
12、总结
目前，mysql不支持对已存在的存储过程修改代码，只能先drop掉重写。
存储过程可以调用其他存储过程
存储过程的参数不要与数据表中的字段同名
存储过程的参数可以使用在中文，不顾需要在定义是加上character set gbk,例如：
mysql > create procedure p1(in u_name varchar(30) character set gbk,out u_score int)