mysql存储过程procedure、函数function的用法

一、存储过程的用法

1.创建语法

CREATE PROCEDURE Pro_name()
BEGIN
...
END 

2.定义变量

DELIMITER $$
CREATE PROCEDURE find_name1()
BEGIN
DECLARE  uid VARCHAR(50) DEFAULT '';
SET uid='004';
  SELECT * FROM student WHERE sid=uid;
  SELECT NAME  FROM test;
END

CALL find_name1();

3.传入一个参数

DELIMITER $$
CREATE PROCEDURE find_name2(uid VARCHAR(20))
BEGIN
  SELECT * FROM student WHERE sid=uid;
END

CALL find_name2('005');

 

4.可以多个begin—end，也可以返回多个参数

 变量作用域说明：
        (1)、存储过程中变量是有作用域的，作用范围在begin和end块之间，end结束变量的作用范围即结束。
        (2)、需要多个块之间传值，可以使用全局变量，即放在所有代码块之前
        (3)、传参变量是全局的，可以在多个块之间起作用

DELIMITER $$
CREATE PROCEDURE find_name5()
BEGIN
BEGIN
  DECLARE max_test INT DEFAULT 0;
  DECLARE max_student INT DEFAULT 0;
  SELECT MAX(age) INTO max_test FROM test;
  SELECT MAX(age) INTO max_student FROM student;
SELECT max_test,max_student;
END;
BEGIN
  DECLARE count_test INT DEFAULT 0;
  DECLARE count_student INT DEFAULT 0;
  SELECT COUNT(0) INTO count_test FROM test;
  SELECT COUNT(0) INTO count_student FROM student;
SELECT count_test,count_student;
END;
END

CALL find_name5();

5.测试全局变量

DELIMITER $$
CREATE PROCEDURE find_name6()
BEGIN
  DECLARE max_test INT DEFAULT 0;
  DECLARE max_student INT DEFAULT 0;
BEGIN
  SELECT MAX(age) INTO max_test FROM test;
  SELECT MAX(age) INTO max_student FROM student;
SELECT max_test;
END;
BEGIN
  DECLARE count_test INT DEFAULT 0;
  DECLARE count_student INT DEFAULT 0;
  SELECT COUNT(0) INTO count_test FROM test;
  SELECT COUNT(0) INTO count_student FROM student;
SELECT max_student,count_test,count_student;
END;
END

CALL find_name6

6.in、out参数的用法

in为传入参数，out为输出参数

DELIMITER $$
CREATE PROCEDURE find_name7(IN id VARCHAR(3),OUT myname VARCHAR(100))
BEGIN
   SELECT sname INTO myname FROM student WHERE sid=id;
END;

CALL find_name7('001',@myname);

SELECT @myname

7.参数inoutde的使用(既能输入一个值又能传出来一个值)

DELIMITER $$
CREATE PROCEDURE find_name8(INOUT myage INT(20))
BEGIN
SET myage=myage+1;
SELECT age INTO myage FROM student WHERE age=myage;
END

SET @myage=20;

CALL find_name8(@myage);

SELECT @myage

也可以写多个inout参数

DELIMITER $$  
CREATE PROCEDURE find_name9(INOUT uid VARCHAR(20),INOUT uname VARCHAR(20))
BEGIN
SET uid='002';
SET uname='';
SELECT sid,sname INTO uid,uname FROM student WHERE sid=uid;
END

CALL find_name9(@uid,@uname);
SELECT @uid,@uname
 

8.存储过程条件语句用法

①条件语句基本结构 if() then...else...end if;

案例：传入一个年龄，如果年龄为偶数，查询名字，否则查询年龄

DELIMITER $$
CREATE PROCEDURE pro_test1(IN myage INT(20))
BEGIN
  DECLARE username VARCHAR(200) DEFAULT '';
  IF(myage%2=0) 
  THEN
    SELECT sname INTO username FROM student WHERE age=myage;
    SELECT username;
  ELSE
    SELECT myage;
  END IF;
END

CALL pro_test1(20)

CALL pro_test1(21)

②多条件判断语句：

if() then...
elseif() then...
else ...
end if;

案例：传入id，查询性别，如果为男人，年龄+10，女人年龄+5，中性人年龄+2

DELIMITER $$
CREATE PROCEDURE pro_test2(IN id VARCHAR(20))
BEGIN
  DECLARE yousex VARCHAR(20) DEFAULT '';
  DECLARE youage INT DEFAULT 0;
  DECLARE yage INT DEFAULT 0;
  SELECT sex ,age INTO yousex,youage FROM student WHERE sid=id;
  SELECT age INTO yage FROM student WHERE sid=id;
  IF(yousex='男')
  THEN
    SET youage=youage+10;
  ELSEIF(yousex='女')
  THEN
    SET youage=youage+5;
  ELSE
    SET youage=youage+2;
  END IF;
  SELECT yage,yousex,youage;
END

CALL pro_test2('001')

CALL pro_test2('002')

CALL pro_test2('003')

9.存储过程循环语句

①while语句的基本结构

1. while(表达式) do 

2.    ......  

3. end while;

案例：循环插入几千条数据

DELIMITER $$                -- 以delimiter来标记用$表示存储过程结束
CREATE  PROCEDURE pro_insert1()     -- 创建pro_insert()存储方法    
BEGIN
DECLARE i INT;             -- 定义i变量
SET i=500;             -- 对i赋值
WHILE 400     INSERT INTO test (id,NAME,age)VALUES(i,'张三',i); 
SET i=i-1;                        -- 自减循环        
END WHILE;              -- 结束while循环
END

CALL pro_insert1()