存储过程
1.存储过程由一组特定功能的SQL语句组成，对于大型应用程序优势较大，相对不使用存储过程，具有以下优点：
a.性能提高，因为存储过程是预编译的，只需编译一次，以后调用就不须再编译
b.重用性提高，可以“一次编写，随便调用”
c.安全性提高，可以一定程度上防止SQL注入，还可以使用权限控制
d.减少网络流量，提高网站访问速度
2.存储过程的建立，使用create procedure语句，语法如下
CREATE
[DEFINER = { user | CURRENT_USER }]
PROCEDURE sp_name ([proc_parameter[,...]])
[characteristic ...] routine_body
CREATE
[DEFINER = { user | CURRENT_USER }]
FUNCTION sp_name ([func_parameter[,...]])
RETURNS type
[characteristic ...] routine_body
proc_parameter:
[ IN | OUT | INOUT ] param_name type
func_parameter:
param_name type
type:
Any valid MySQL data type
示例：
use test; delimiter $$ //改变语句分隔符 create procedure test(in a varchar(10),out b int) //in 输入参数 out 输出 inout 输入输出 begin select concat(‘hello ‘,a); select count(1) into b from tb_6; end$$ delimiter ; call test(‘world‘,@c); //使用call调用存储过程 select @c;
参数为INOUT示例
delimiter $$ create procedure test(inout b int) begin select b; set b=10; select b; select count(1) into b from tb_5; end$$ delimiter ; set @b = 100; call test(@b); select @b; --------------------------结果----------------------- mysql> call test(@b); +------+ | b | +------+ | 20 | +------+ 1 row in set (0.00 sec) +------+ | b | +------+ | 10 | +------+ 1 row in set (0.01 sec) Query OK, 1 row affected (0.04 sec) mysql> select @b; +--------+ | @b | +--------+ | 120832 | +--------+ 1 row in set (0.00 sec)
变量的定义，赋值，以及用户变量示例
delimiter $$ create procedure test() begin declare i int default 1; --变量的定义 select i; set i = 100; --变量的赋值 select i; end$$ delimiter ; //结果 mysql> call test(); +------+ | i | +------+ | 1 | +------+ 1 row in set (0.00 sec) +------+ | i | +------+ | 100 | +------+ 1 row in set (0.01 sec) mysql> set @t=‘hehe‘; --用户变量 Query OK, 0 rows affected (0.00 sec) mysql> select @t; +------+ | @t | +------+ | hehe | +------+ 1 row in set (0.00 sec)
3.存储过程的更改，删除
ALTER PROCEDURE proc_name [characteristic ...] drop procedure proc_name
4.查看存储过程的信息
mysql> select name from mysql.proc where db=‘test‘; +----------+ | name | +----------+ | add_user | | partPage | | test | +----------+ 3 rows in set (0.00 sec) --或者使用show create procedure proc_name
5.存储过程的控制结构
if-then-else-end if语句
delimiter $$ create procedure proc(in i int,out res varchar(30)) begin declare j int; set j = 20; if i<j then set res = ‘i is smaller than j‘; else set res = ‘i is bigger than j‘; end if; end --结果 mysql> call proc(30,@ret); Query OK, 0 rows affected (0.00 sec) mysql> select @ret; +--------------------+ | @ret | +--------------------+ | i is bigger than j | +--------------------+ 1 row in set (0.00 sec)
case-when-then-end case语句
delimiter $$ create procedure proc(in i int,out res varchar(30)) begin case i when 1 then set res=‘星期一‘; when 1 then set res=‘星期二‘; when 1 then set res=‘星期三‘; when 1 then set res=‘星期四‘; when 1 then set res=‘星期五‘; when 1 then set res=‘星期六‘; when 1 then set res=‘星期日‘; end case; end$$ --结果 mysql> call proc(1,@ret); Query OK, 0 rows affected (0.03 sec) mysql> select @ret; +--------+ | @ret | +--------+ | 星期一 | +--------+ 1 row in set (0.03 sec)
循环while-do-end while语句
DELIMITER $$ CREATE PROCEDURE `add_user`() begin declare i int default 1; while i<=50 do insert into users(userName,email,passwd,registion_date) values(concat(‘zhumuxian‘,i),concat(‘zhumuxian‘,i,‘@163.com‘),sha1(‘1234567‘),now()); set i=i+1; end while; end
示例，分页存储过程
CREATE PROCEDURE `partPage`(in perPageNum int ,in currentPage int) begin declare perNum int default 10; declare curPage int default 1; declare start0 int ; set perNum=perPageNum; set curPage=currentPage; set start0=(curPage-1)*perNum; select user_id,userName,email,registion_date from users limit start0,perNum; end
存储函数与存储过程在语法上有点类似，不同点：
存储函数需要返回一个类型，且函数体中必须要有一个有效的return语句。
它们调用的方式不同，过程使用call调用，函数使用select调用。
函数只能返回一个结果值，而过程可以返回一个或多个结果集，等等。
存储函数的创建，语法如下
CREATE
[DEFINER = { user | CURRENT_USER }]
FUNCTION sp_name ([func_parameter[,...]])
RETURNS type
[characteristic ...] routine_body
创建示例
delimiter $$ create function getDate() returns varchar(255) begin declare str varchar(255) default ‘0000-00-00 00:00:00‘; set str = date_format(now(),‘%Y年%m月%d日 %H时%i分%S秒‘); return str; end $$ delimiter ; --结果 mysql> select getDate(); +-----------------------------+ | getDate() | +-----------------------------+ | 2015年04月16日 15时16分46秒 | +-----------------------------+ 1 row in set (0.08 sec)
如在创建函数时碰到ERROR 1418 (HY000)错误，可以设置log_bin_trust_function_creators=TRUE即可。
mysql> show variables like ‘log_bin_trust_function_creators‘; +---------------------------------+-------+ | Variable_name | Value | +---------------------------------+-------+ | log_bin_trust_function_creators | ON | +---------------------------------+-------+ 1 row in set (0.00 sec)
分支结构示例
delimiter $$ create function sub_str(str varchar(255),n int) returns varchar(255) begin if isnull(str) then return ‘‘; elseif char_length(str)<n then return str; else return left(str,n); end if; end$$ delimiter ; --结果 mysql> select sub_str(‘wozhidaole‘,1); +-------------------------+ | sub_str(‘wozhidaole‘,1) | +-------------------------+ | w | +-------------------------+ 1 row in set (0.00 sec)
触发器，是一种特殊的存储过程，在特定表执行更新，插入，删除操作时触发，具有更好的数据控制能力，创建语法如下：
CREATE TRIGGER trigger_name trigger_time trigger_event ON tbl_name FOR EACH ROW trigger_body
示例
delimiter $$ create trigger pp after insert on t1 for each row begin insert into t2 values (new.id); end$$ delimiter ;
删除触发器
mysql> drop trigger pp; Query OK, 0 rows affected (0.00 sec)
查看所有触发器
mysql> show triggers\G
*************************** 1. row ***************************
Trigger: pp
Event: INSERT
Table: t1
Statement: begin
insert into t2 values (new.id);
end
Timing: AFTER
Created: NULL
sql_mode: STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
Definer: root@localhost
character_set_client: utf8
collation_connection: utf8_general_ci
Database Collation: utf8_general_ci
1 row in set (0.01 sec)
查看某一个触发器信息
mysql> show create trigger pp\G
*************************** 1. row ***************************
Trigger: pp
sql_mode: STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
SQL Original Statement: CREATE DEFINER=`root`@`localhost` trigger pp after insert on t1 for each row
begin
insert into t2 values (new.id);
end
character_set_client: utf8
collation_connection: utf8_general_ci
Database Collation: utf8_general_ci
1 row in set (0.00 sec)
mysql> select * from information_schema.triggers where trigger_name=‘pp‘\G
*************************** 1. row ***************************
TRIGGER_CATALOG: def
TRIGGER_SCHEMA: test
TRIGGER_NAME: pp
EVENT_MANIPULATION: INSERT
EVENT_OBJECT_CATALOG: def
EVENT_OBJECT_SCHEMA: test
EVENT_OBJECT_TABLE: t1
ACTION_ORDER: 0
ACTION_CONDITION: NULL
ACTION_STATEMENT: begin
insert into t2 values (new.id);
end
ACTION_ORIENTATION: ROW
ACTION_TIMING: AFTER
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULL
ACTION_REFERENCE_OLD_ROW: OLD
ACTION_REFERENCE_NEW_ROW: NEW
CREATED: NULL
SQL_MODE: STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
DEFINER: root@localhost
CHARACTER_SET_CLIENT: utf8
COLLATION_CONNECTION: utf8_general_ci
DATABASE_COLLATION: utf8_general_ci
1 row in set (0.09 sec)
时间： 2024-11-03 03:33:25