6-存储过程

标签：into   rop   孙悟空   row   rom   erro   float   roc   猪八戒   

1、基本语法示例，局部变量+用户变量

1.1 基本语法

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.49 sec)

mysql> delimiter //
mysql> create procedure t1()
    -> begin
    -> declare mm int default 5;
    -> select mm;
    -> end //
Query OK, 0 rows affected (0.12 sec)

mysql> delimiter ;
mysql> call t1();
+------+
| mm   |
+------+
|    5 |
+------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

1.2 局部变量+用户变量

mysql> set @mm=3;
Query OK, 0 rows affected (0.00 sec)

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.39 sec)

mysql> delimiter //
mysql> create procedure t1()
    -> begin
    -> declare mm int;
    -> select @mm;
    -> set mm=5;
    -> select mm;
    -> end //
Query OK, 0 rows affected (0.07 sec)

mysql> delimiter ;
mysql> call t1();
+------+
| @mm  |
+------+
|    3 |
+------+
1 row in set (0.00 sec)

+------+
| mm   |
+------+
|    5 |
+------+
1 row in set (0.01 sec)

Query OK, 0 rows affected (0.01 sec)

# 注：{set @mm=3}为用户变量，用户范围内生效；{declare mm int; set mm=10}为局部变量，仅在存储过程内生效

2、流程控制语句

2.1 if条件判断

• 语法：

if 条件 then
SQL语句;
elseif 条件 then
SQL语句;
else SQL语句;
end if;

• 需求：创建存储过程。插入的score：
  • 大于等于80分，level为优秀；
  • 大于等于60分，level为及格；
  • 小于60分，level为不及格；
  • 小于0或大于100，输出“请输入正确的分数”

mysql> desc mm2;
+-------+-------------------------------------+------+-----+---------+-------+
| Field | Type                                | Null | Key | Default | Extra |
+-------+-------------------------------------+------+-----+---------+-------+
| name  | varchar(10)                         | YES  |     | NULL    |       |
| score | int                                 | YES  |     | NULL    |       |
| level | enum(‘优秀‘,‘及格‘,‘不及格‘)        | YES  |     | NULL    |       |
+-------+-------------------------------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.53 sec)

mysql> delimiter //
mysql> create procedure t1(name varchar(10),sc int)
    -> begin
    -> if sc>100 or sc<0 then
    -> select ‘请输入正确的分数‘;
    -> elseif sc>=80 then
    -> insert into mm2 values (name,sc,‘优秀‘);
    -> elseif sc>=60 then
    -> insert into mm2 values (name,sc,‘及格‘);
    -> else
    -> insert into mm2 values (name,sc,‘不及格‘);
    -> end if;
    -> end //
Query OK, 0 rows affected (0.08 sec)

mysql> delimiter ;

mysql> call t1(‘张三‘,‘85‘);
Query OK, 1 row affected, 1 warning (0.11 sec)

mysql> call t1(‘李四‘,‘77‘);
Query OK, 1 row affected (0.08 sec)

mysql> call t1(‘王五‘,‘52‘);
Query OK, 1 row affected (0.40 sec)

mysql> call t1(‘孙悟空‘,‘220‘);
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> call t1(‘猪八戒‘,‘-22‘);
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> select * from mm2;
+--------+-------+-----------+
| name   | score | level     |
+--------+-------+-----------+
| 张三   |    85 | 优秀      |
| 李四   |    77 | 及格      |
| 王五   |    52 | 不及格    |
+--------+-------+-----------+
3 rows in set (0.00 sec)

2.2 case条件判断

• 语法1：

case 变量
when 值1 then
SQL语句;
when 值2 then
SQL语句;
else
SQL语句;
end case;

• 语法2：

case
when 条件1 then
SQL语句;
when 条件2 then
SQL语句;
···
end case;

• 需求1：同2.1需求

mysql> drop procedure if exists t1;
Query OK, 0 rows affected, 1 warning (0.33 sec)

mysql> delimiter //
mysql> create procedure t1(name varchar(10),sc int)
    -> begin
    -> case
    -> when sc>100 or sc<0 then
    -> select ‘请输入正确的分数‘;
    -> when sc>=80 then
    -> insert into mm2 values (name,sc,‘优秀‘);
    -> when sc>=60 then
    -> insert into mm2 values (name,sc,‘及格‘);
    -> else
    -> insert into mm2 values (name,sc,‘不及格‘);
    -> end case;
    -> end //
Query OK, 0 rows affected (0.10 sec)

mysql> delimiter ;
mysql> call t1(‘杨过‘,‘15‘);
Query OK, 1 row affected, 1 warning (0.39 sec)

mysql> call t1(‘梅超风‘,‘75‘);
Query OK, 1 row affected (0.12 sec)

mysql> call t1(‘郭靖‘,‘99‘);
Query OK, 1 row affected (0.07 sec)

mysql> call t1(‘小李‘,‘103‘);
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> call t1(‘天天‘,‘-1‘);
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
| 请输入正确的分数         |
+--------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> select * from mm2;
+-----------+-------+-----------+
| name      | score | level     |
+-----------+-------+-----------+
| 杨过      |    15 | 不及格    |
| 梅超风    |    75 | 及格      |
| 郭靖      |    99 | 优秀      |
+-----------+-------+-----------+
3 rows in set (0.00 sec)

• 需求2：创建存储过程。插入score：
  • 值为0，level为退学；
  • 值为99，level为很棒；
  • 值为100，level为最棒。

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.52 sec)

mysql> delimiter //
mysql> create procedure t1(name varchar(10),sc int)
    -> begin
    -> case sc
    -> when ‘0‘ then
    -> insert into mm2 values (name,sc,‘退学‘);
    -> when ‘99‘ then
    -> insert into mm2 values (name,sc,‘很棒‘);
    -> when ‘100‘ then
    -> insert into mm2 values (name,sc,‘最棒‘);
    -> end case;
    -> end //
Query OK, 0 rows affected (0.15 sec)

mysql> delimiter ;
mysql> call t1(‘大蛇丸‘,‘0‘);
Query OK, 1 row affected, 1 warning (0.09 sec)

mysql> call t1(‘自来也‘,‘99‘);
Query OK, 1 row affected (0.42 sec)

mysql> call t1(‘纲手‘,‘100‘);
Query OK, 1 row affected (0.09 sec)

mysql> call t1(‘小樱‘,‘80‘);
ERROR 1339 (20000): Case not found for CASE statement
mysql> select * from mm2;
+-----------+-------+-----------+
| name      | score | level     |
+-----------+-------+-----------+
| 大蛇丸    |     0 | 退学      |
| 自来也    |    99 | 很棒      |
| 纲手      |   100 | 最棒      |
+-----------+-------+-----------+
6 rows in set (0.00 sec)

2.3 while循环

• 语法：

while 条件 do
SQL语句；
end while;

• 需求：向mm1表插入1-10

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.12 sec)

mysql> delimiter //
mysql> create procedure t1()
    -> begin
    -> declare i int default 1;
    -> while i<=10 do
    -> insert into mm1 values (i);
    -> set i=i+1;
    -> end while;
    -> end //
Query OK, 0 rows affected (0.09 sec)

mysql> delimiter ;
mysql> call t1();
Query OK, 1 row affected (0.90 sec)

mysql> select * from mm1;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
|    5 |
|    6 |
|    7 |
|    8 |
|    9 |
|   10 |
+------+
10 rows in set (0.00 sec)

2.4 repeat循环

• 语法：

repeat
SQL语句；
until 条件
end repeat;

• 需求：同2.3

mysql> drop procedure if exists t1;
Query OK, 0 rows affected (0.15 sec)

mysql> delimiter //
mysql> create procedure t1()
    -> begin
    -> declare i int default 1;
    -> repeat
    -> insert into mm1 values (i);
    -> set i=i+1;
    -> until i>10
    -> end repeat;
    -> end //
Query OK, 0 rows affected (0.22 sec)

mysql> delimiter ;
mysql> call t1();
Query OK, 1 row affected (0.62 sec)

mysql> select * from mm1;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
|    5 |
|    6 |
|    7 |
|    8 |
|    9 |
|   10 |
+------+
10 rows in set (0.00 sec)

2.5 loop循环

• 语法：

loop
标签名: loop
SQL语句;
if 条件 then
leave 标签名;
end if;
end loop 标签名;
# 注：loop循环无法跳出循环，需借助{if…then…leave}跳出

• 需求：同2.3

mysql> drop procedure if exists t1;
Query OK, 0 rows affected, 1 warning (0.06 sec)

mysql> delimiter //
mysql> create procedure t1()
    -> begin
    -> declare i int default 1;
    -> bbc: loop
    -> insert into mm1 values (i);
    -> set i=i+1;
    -> if i>10 then
    -> leave bbc;
    -> end if;
    -> end loop bbc;
    -> end //
Query OK, 0 rows affected (0.07 sec)

mysql> delimiter ;
mysql> call t1();
Query OK, 1 row affected (0.68 sec)

mysql> select * from mm1;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
|    5 |
|    6 |
|    7 |
|    8 |
|    9 |
|   10 |
+------+
10 rows in set (0.00 sec)

2.6 in、out、inout

• 2.6.1 in输入参数

mysql> delimiter //
mysql> create procedure in_param(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 in_param(@p_in);
+------+
| p_in |
+------+
|    1 |
+------+

+------+
| P_in |
+------+
|    2 |
+------+

mysql> select @p_in;
+-------+
| @p_in |
+-------+
|     1 |
+-------+

• 2.6.2 out输入参数

mysql> delimiter //
mysql> create procedure out_param(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 out_param(@p_out);
+-------+
| p_out |
+-------+
|  NULL |
+-------+
　　#因为out是向调用者输出参数，不接收输入的参数，所以存储过程里的p_out为null
+-------+
| p_out |
+-------+
|     2 |
+-------+

mysql> select @p_out;
+--------+
| @p_out |
+--------+
|      2 |
+--------+

• 2.6.3 inout输入参数

mysql> delimiter //
mysql> create procedure inout_param(inout p_inout int)
    ->   begin
    ->     select p_inout;
    ->     set p_inout=2;
    ->     select p_inout;
    ->   end //
mysql> delimiter ;

mysql> set @p_inout=1;

mysql> call inout_param(@p_inout);
+---------+
| p_inout |
+---------+
|       1 |
+---------+

+---------+
| p_inout |
+---------+
|       2 |
+---------+

mysql> select @p_inout;
+----------+
| @p_inout |
+----------+
|        2 |
+----------+

• 2.6.4 select…into…

CREATE PROCEDURE zichan(in i_type varchar(20))
begin
declare s_type varchar(20);
declare s_name varchar(20);
declare s_money float;
select t2.type,t3.name,t1.money into s_type,s_name,s_money from t_zichan t1
left join t_zichan_type t2
on t1.type = t2.id
left join t_renyuan t3
on t1.owner = t3.id
where t2.type like concat(‘%‘,i_type,‘%‘);
select s_type,s_name,s_money;
end

6-存储过程

标签：into   rop   孙悟空   row   rom   erro   float   roc   猪八戒   

原文地址：https://www.cnblogs.com/ly447742/p/14176697.html