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');

 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;