MySQLデータベースのストアドプロシージャとストアド関数の強化演習
序文
この環境は、
特定の構築のためにMySQL-5.7.14を構築するためのCentos7.8システムに基づいています。MySQL-5.7.14環境構築を参照してください。
sch 表结构
字段名 数据类型 主键 外键 非空 唯一 自增
id INT 是 否 是 是 否
name VARCHAR(50) 否 否 是 否 否
glass VARCHAR(50) 否 否 是 否 否
sch 表内容
id name glass
1 xiaommg glass 1
2 xiaojun glass 2
1、创建一个可以统计表格内记录条数的存储函数 ，函数名为count_sch()
创建sch表：
mysql> create table sch
-> (id int primary key auto_increment,
-> name varchar(50) not null,
-> glass varchar(50) not null);
Query OK, 0 rows affected (0.00 sec)
mysql> desc sch;
+-------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(50) | NO | | NULL | |
| glass | varchar(50) | NO | | NULL | |
+-------+-------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
mysql> insert into sch
-> values(1,'xiaoming','glass 1'),(2,'xiaojun','glass 2');
Query OK, 2 rows affected (0.01 sec)
mysql> select * from sch;
+----+----------+---------+
| id | name | glass |
+----+----------+---------+
| 1 | xiaoming | glass 1 |
| 2 | xiaojun | glass 2 |
+----+----------+---------+
2 rows in set (0.00 sec)
mysql> \d $
mysql> create function count_stu_num()
-> returns int
-> begin
-> declare num int;
-> select count(1) into num from sch;
-> return num;
-> end $
Query OK, 0 rows affected (0.00 sec)
mysql> \d ;
mysql> select count_stu_num();
+-----------------+
| count_stu_num() |
+-----------------+
| 2 |
+-----------------+
1 row in set (0.00 sec)
2、创建一个存储过程avg_sai，有3个参数，分别是deptno，job，接收平均工资，功能查询emp表dept为30，job为销售员的平均工资。（使用之前的emp表）
# 创建emp表
/* 素材 */
CREATE TABLE `emp` (
`empno` int(4) NOT NULL,
`ename` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`job` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`mgr` int(4) NULL DEFAULT NULL,
`hiredate` date NOT NULL,
`sai` int(255) NOT NULL,
`comm` int(255) NULL DEFAULT NULL,
`deptno` int(2) NOT NULL,
PRIMARY KEY (`empno`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
INSERT INTO `emp` VALUES (1001, '甘宁', '文员', 1013, '2000-12-17', 8000, NULL, 20);
INSERT INTO `emp` VALUES (1002, '黛绮丝', '销售员', 1006, '2001-02-20', 16000, 3000, 30);
INSERT INTO `emp` VALUES (1003, '殷天正', '销售员', 1006, '2001-02-22', 12500, 5000, 30);
INSERT INTO `emp` VALUES (1004, '刘备', '经理', 1009, '2001-04-02', 29750, NULL, 20);
INSERT INTO `emp` VALUES (1005, '谢逊', '销售员', 1006, '2001-09-28', 12500, 14000, 30);
INSERT INTO `emp` VALUES (1006, '关羽', '经理', 1009, '2001-05-01', 28500, NULL, 30);
INSERT INTO `emp` VALUES (1007, '张飞', '经理', 1009, '2001-09-01', 24500, NULL, 10);
INSERT INTO `emp` VALUES (1008, '诸葛亮', '分析师', 1004, '2007-04-19', 30000, NULL, 20);
INSERT INTO `emp` VALUES (1009, '曾阿牛', '董事长', NULL, '2001-11-17', 50000, NULL, 10);
INSERT INTO `emp` VALUES (1010, '韦一笑', '销售员', 1006, '2001-09-08', 15000, 0, 30);
INSERT INTO `emp` VALUES (1011, '周泰', '文员', 1006, '2007-05-23', 11000, NULL, 20);
INSERT INTO `emp` VALUES (1012, '程普', '文员', 1006, '2001-12-03', 9500, NULL, 30);
INSERT INTO `emp` VALUES (1013, '庞统', '分析师', 1004, '2001-12-03', 30000, NULL, 20);
INSERT INTO `emp` VALUES (1014, '黄盖', '文员', 1007, '2002-01-23', 13000, NULL, 10);
INSERT INTO `emp` VALUES (1015, '张三', '保洁员', 1001, '2013-05-01', 80000, 50000, 50);
mysql> desc emp;
+----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| empno | int(4) | NO | PRI | NULL | |
| ename | varchar(255) | YES | | NULL | |
| job | varchar(255) | YES | | NULL | |
| mgr | int(4) | YES | | NULL | |
| hiredate | date | NO | | NULL | |
| sai | int(255) | NO | | NULL | |
| comm | int(255) | YES | | NULL | |
| deptno | int(2) | NO | | NULL | |
+----------+--------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
mysql> select * from emp;
+-------+-----------+-----------+------+------------+-------+-------+--------+
| empno | ename | job | mgr | hiredate | sai | comm | deptno |
+-------+-----------+-----------+------+------------+-------+-------+--------+
| 1001 | 甘宁 | 文员 | 1013 | 2000-12-17 | 8000 | NULL | 20 |
| 1002 | 黛绮丝 | 销售员 | 1006 | 2001-02-20 | 16000 | 3000 | 30 |
| 1003 | 殷天正 | 销售员 | 1006 | 2001-02-22 | 12500 | 5000 | 30 |
| 1004 | 刘备 | 经理 | 1009 | 2001-04-02 | 29750 | NULL | 20 |
| 1005 | 谢逊 | 销售员 | 1006 | 2001-09-28 | 12500 | 14000 | 30 |
| 1006 | 关羽 | 经理 | 1009 | 2001-05-01 | 28500 | NULL | 30 |
| 1007 | 张飞 | 经理 | 1009 | 2001-09-01 | 24500 | NULL | 10 |
| 1008 | 诸葛亮 | 分析师 | 1004 | 2007-04-19 | 30000 | NULL | 20 |
| 1009 | 曾阿牛 | 董事长 | NULL | 2001-11-17 | 50000 | NULL | 10 |
| 1010 | 韦一笑 | 销售员 | 1006 | 2001-09-08 | 15000 | 0 | 30 |
| 1011 | 周泰 | 文员 | 1006 | 2007-05-23 | 11000 | NULL | 20 |
| 1012 | 程普 | 文员 | 1006 | 2001-12-03 | 9500 | NULL | 30 |
| 1013 | 庞统 | 分析师 | 1004 | 2001-12-03 | 30000 | NULL | 20 |
| 1014 | 黄盖 | 文员 | 1007 | 2002-01-23 | 13000 | NULL | 10 |
| 1015 | 张三 | 保洁员 | 1001 | 2013-05-01 | 80000 | 50000 | 50 |
+-------+-----------+-----------+------+------------+-------+-------+--------+
15 rows in set (0.00 sec)
# 创建存储过程
mysql> \d $$
mysql> create procedure avg_sai(in p1 int,in p2 varchar(255),out p3 int(255))
-> begin
-> select avg(sai) into p3 from emp
-> where empno=p1 or job=p2;
-> end $$
mysql> call avg_sai(30,'销售员',@W);
Query OK, 1 row affected (0.04 sec)
mysql> select @W;
+-------+
| @W |
+-------+
| 14000 |
+-------+
1 row in set (0.00 sec)