数据库function和procedure

数据库初始化：

CREATE DATABASE school;

-- 创建表：course
CREATE TABLE `course` (
`cno` VARCHAR (12) NOT NULL DEFAULT '',
`cname` VARCHAR (12) NOT NULL,
`cpno` VARCHAR (12) DEFAULT NULL,
`ccredit` INT (11) NOT NULL,
PRIMARY KEY (`cno`)
) ENGINE = INNODB DEFAULT CHARSET = utf8;

INSERT INTO `course`
VALUES
('1', 'java', '2', '3');

INSERT INTO `course`
VALUES
('2', 'c++', '4', '2');

INSERT INTO `course`
VALUES
('3', '数学', NULL, '5');

INSERT INTO `course`
VALUES
('4', 'c', '3', '3');

INSERT INTO `course`
VALUES
('5', '英语', NULL, '5');

INSERT INTO `course`
VALUES
('6', '数据结构', '3', '3');

INSERT INTO course
VALUES
('7', 'c', '3', '5');

DELETE
FROM
course
WHERE
cno = '7';

CREATE TABLE `student` (
`id` INT (11) NOT NULL,
`sno` VARCHAR (12) NOT NULL,
`sname` VARCHAR (12) NOT NULL,
`ssex` VARCHAR (1) DEFAULT '女',
`sage` INT (11) NOT NULL,
`sdept` VARCHAR (12) NOT NULL,
`sprovince` VARCHAR (255) DEFAULT NULL,
`scity` VARCHAR (255) DEFAULT NULL,
`sstreet` VARCHAR (255) DEFAULT NULL,
`sbirthday` date DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `sno` (`sno`),
FULLTEXT KEY `index_name` (`sname`)
) ENGINE = INNODB DEFAULT CHARSET = utf8;

INSERT INTO `student`
VALUES
(
'2',
'002',
'李丽',
'女',
'19',
'数学系',
'江苏',
'苏州',
'长桥',
'1997-07-18'
);

INSERT INTO `student`
VALUES
(
'3',
'003',
'李彤',
'女',
'22',
'数学系',
'江苏',
'南京',
'解放',
'1994-08-02'
);

INSERT INTO `student`
VALUES
(
'4',
'004',
'张天宇',
'男',
'25',
'计算机科学与技术系',
'上海',
'上海',
'仁义',
'1991-07-07'
);

INSERT INTO `student`
VALUES
(
'5',
'005',
'李大奎',
'男',
'20',
'计算机科学与技术系',
'浙江',
'杭州',
'东营',
'1996-02-08'
);

INSERT INTO `student`
VALUES
(
'6',
'006',
'张思源',
'男',
'27',
'数学系',
'广东',
'深圳',
'华强',
'1989-02-06'
);

INSERT INTO `student`
VALUES
(
'7',
'007',
'tony',
'男',
'20',
'中文',
'浙江',
'杭州',
'东营',
'1996-05-29'
);

INSERT INTO `student`
VALUES
(
'9',
'0l9',
'nicy',
'女',
'21',
'中文',
NULL,
NULL,
NULL,
NULL
);

CREATE TABLE `sc` (
`id` INT (11) NOT NULL AUTO_INCREMENT,
`sno` VARCHAR (12) NOT NULL,
`cno` VARCHAR (12) NOT NULL,
`grade` INT (11) NOT NULL,
PRIMARY KEY (`id`),
KEY `sno` (`sno`),
KEY `cno` (`cno`),
CONSTRAINT `sc_ibfk_1` FOREIGN KEY (`sno`) REFERENCES `student` (`sno`),
CONSTRAINT `sc_ibfk_2` FOREIGN KEY (`cno`) REFERENCES `course` (`cno`)
) ENGINE = INNODB AUTO_INCREMENT = 9 DEFAULT CHARSET = utf8;

INSERT INTO `sc`
VALUES
('1', '002', '2', '50');

INSERT INTO `sc`
VALUES
('2', '002', '3', '70');

INSERT INTO `sc`
VALUES
('3', '003', '2', '30');

INSERT INTO `sc`
VALUES
('4', '005', '3', '95');

INSERT INTO `sc`
VALUES
('5', '003', '4', '100');

INSERT INTO `sc`
VALUES
('6', '002', '4', '90');

INSERT INTO `sc`
VALUES
('7', '004', '4', '70');

INSERT INTO `sc`
VALUES
('8', '005', '4', '90');

CREATE TABLE `test` (
`id` VARCHAR (255) NOT NULL,
`name` VARCHAR (255) NOT NULL,
`birthday` date DEFAULT NULL
) ENGINE = INNODB DEFAULT CHARSET = utf8;

INSERT INTO `test`
VALUES
('001', 'tom', NULL);

INSERT INTO `test`
VALUES
('002', 'tony', NULL);

INSERT INTO `test`
VALUES
('0l3', 'helen', NULL);

INSERT INTO `test`
VALUES
('003', 'jack', '2015-08-17');

INSERT INTO `test`
VALUES
('004', 'jack', '2015-03-05');

INSERT INTO `test`
VALUES
('005', 'jack', '2015-03-05');

View Code
创建函数：

CREATE FUNCTION fun_getage(str varchar(10))
-- 函数必须带返回值
RETURNS VARCHAR(10)
BEGIN
RETURN (SELECT sage FROM student WHERE sname=str);
END;

调用函数：

SELECT fun_getage('李丽');

output：

19

在函数中声明变量：

CREATE FUNCTION fun_getcorce(stu_name VARCHAR(10),course_name varchar(10))
RETURNS INT
BEGIN
DECLARE corce INT;
SET corce=0;
--     还可以用 DECLARE corce_temp INT DEFAULT 0; 声明变量。
SELECT sc.grade INTO corce FROM sc
WHERE sc.sno=(SELECT student.sno FROM student WHERE student.sname=stu_name)
AND sc.cno=(SELECT course.cno from course where course.cname=course_name);
RETURN corce;
END;

在函数中使用 if 语句：

CREATE FUNCTION fun_isPass(stu_name VARCHAR(10),course_name VARCHAR(10))
RETURNS VARCHAR(10)
BEGIN
DECLARE stu_core INT DEFAULT 0;
DECLARE res VARCHAR(10) DEFAULT '';
SELECT grade INTO stu_core FROM stu_sno_sname_cname_grade_view WHERE sname=stu_name AND cname=course_name;
IF stu_core>60 AND stu_core<100 THEN SET res ='及格';
ELSEIF stu_core=100 THEN SET res='满分';
ELSEIF stu_core<60 THEN SET res ='不及格';
END IF;
RETURN res ;
END;

使用procedure:

创建存储过程：

CREATE PROCEDURE pro_test()
BEGIN
SELECT 'hello world';
END;

调用procedure:

CALL pro_test();

创建一个带输入参数的procedure：

CREATE PROCEDURE pro_test1(in n INT)
BEGIN
SELECT n*n;
END;

调用：

CALL pro_test1(10);
-- 或
SET @n =20;
CALL pro_test1(@n);

带返回参数的procedure：

CREATE PROCEDURE pro_test2(in n int,INOUT m INT)
BEGIN
SET m=n*m;
END;

IN表示输入参数，OUT表示输出，INOUT表示既可以输入也可以输出。

调用：

SET @n=10;
SET @m=20;
CALL pro_test2(@n,@m);
SELECT @m;

在procedure中使用循环：

CREATE PROCEDURE pro_add_grade()
BEGIN
DECLARE grade_temp INT DEFAULT 0;
SELECT MIN(grade) INTO grade_temp FROM sc;
WHILE grade_temp < 60 DO
UPDATE sc SET grade=grade+10;
SELECT MIN(grade) INTO grade_temp FROM sc;
END WHILE;
UPDATE sc SET grade=100 WHERE grade > 100;
END;