130 lines
7.4 KiB
SQL
130 lines
7.4 KiB
SQL
-- ===========================条件查询=======================
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-- 数据准备
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-- 员工管理(带约束)
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create table tb_emp (
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id int unsigned primary key auto_increment comment 'ID',
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username varchar(20) not null unique comment '用户名',
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password varchar(32) default '123456' comment '密码',
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name varchar(10) not null comment '姓名',
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gender tinyint unsigned not null comment '性别, 说明: 1 男, 2 女',
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image varchar(300) comment '图像',
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job tinyint unsigned comment '职位, 说明: 1 班主任,2 讲师, 3 学工主管, 4 教研主管',
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entrydate date comment '入职时间',
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create_time datetime not null comment '创建时间',
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update_time datetime not null comment '修改时间'
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) comment '员工表';
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-- 准备测试数据
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INSERT INTO tb_emp (id, username, password, name, gender, image, job, entrydate, create_time, update_time)
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VALUES
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(1, 'jinyong', '123456', '金庸', 1, '1.jpg', 4, '2000-01-01', '2022-10-27 16:35:33', '2022-10-27 16:35:35'),
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(2, 'zhangwuji', '123456', '张无忌', 1, '2.jpg', 2, '2015-01-01', '2022-10-27 16:35:33', '2022-10-27 16:35:37'),
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(3, 'yangxiao', '123456', '杨逍', 1, '3.jpg', 2, '2008-05-01', '2022-10-27 16:35:33', '2022-10-27 16:35:39'),
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(4, 'weiyixiao', '123456', '韦一笑', 1, '4.jpg', 2, '2007-01-01', '2022-10-27 16:35:33', '2022-10-27 16:35:41'),
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(5, 'changyuchun', '123456', '常遇春', 1, '5.jpg', 2, '2012-12-05', '2022-10-27 16:35:33', '2022-10-27 16:35:43'),
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(6, 'xiaozhao', '123456', '小昭', 2, '6.jpg', 3, '2013-09-05', '2022-10-27 16:35:33', '2022-10-27 16:35:45'),
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(7, 'jixiaofu', '123456', '纪晓芙', 2, '7.jpg', 1, '2005-08-01', '2022-10-27 16:35:33', '2022-10-27 16:35:47'),
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(8, 'zhouzhiruo', '123456', '周芷若', 2, '8.jpg', 1, '2014-11-09', '2022-10-27 16:35:33', '2022-10-27 16:35:49'),
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(9, 'dingminjun', '123456', '丁敏君', 2, '9.jpg', 1, '2011-03-11', '2022-10-27 16:35:33', '2022-10-27 16:35:51'),
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(10, 'zhaomin', '123456', '赵敏', 2, '10.jpg', 1, '2013-09-05', '2022-10-27 16:35:33', '2022-10-27 16:35:53'),
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(11, 'luzhangke', '123456', '鹿杖客', 1, '11.jpg', 2, '2007-02-01', '2022-10-27 16:35:33', '2022-10-27 16:35:55'),
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(12, 'hebiweng', '123456', '鹤笔翁', 1, '12.jpg', 2, '2008-08-18', '2022-10-27 16:35:33', '2022-10-27 16:35:57'),
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(13, 'fangdongbai', '123456', '方东白', 1, '13.jpg', 1, '2012-11-01', '2022-10-27 16:35:33', '2022-10-27 16:35:59'),
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(14, 'zhangsanfeng', '123456', '张三丰', 1, '14.jpg', 2, '2002-08-01', '2022-10-27 16:35:33', '2022-10-27 16:36:01'),
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(15, 'yulianzhou', '123456', '俞莲舟', 1, '15.jpg', 2, '2011-05-01', '2022-10-27 16:35:33', '2022-10-27 16:36:03'),
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(16, 'songyuanqiao', '123456', '宋远桥', 1, '16.jpg', 2, '2010-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:05'),
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(17, 'chenyouliang', '12345678', '陈友谅', 1, '17.jpg', null, '2015-03-21', '2022-10-27 16:35:33', '2022-10-27 16:36:07'),
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(18, 'zhang1', '123456', '张一', 1, '2.jpg', 2, '2015-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:09'),
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(19, 'zhang2', '123456', '张二', 1, '2.jpg', 2, '2012-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:11'),
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(20, 'zhang3', '123456', '张三', 1, '2.jpg', 2, '2018-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:13'),
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(21, 'zhang4', '123456', '张四', 1, '2.jpg', 2, '2015-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:15'),
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(22, 'zhang5', '123456', '张五', 1, '2.jpg', 2, '2016-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:17'),
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(23, 'zhang6', '123456', '张六', 1, '2.jpg', 2, '2012-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:19'),
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(24, 'zhang7', '123456', '张七', 1, '2.jpg', 2, '2006-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:21'),
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(25, 'zhang8', '123456', '张八', 1, '2.jpg', 2, '2002-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:23'),
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(26, 'zhang9', '123456', '张九', 1, '2.jpg', 2, '2011-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:25'),
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(27, 'zhang10', '123456', '张十', 1, '2.jpg', 2, '2004-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:27'),
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(28, 'zhang11', '123456', '张十一', 1, '2.jpg', 2, '2007-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:29'),
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(29, 'zhang12', '123456', '张十二', 1, '2.jpg', 2, '2020-01-01', '2022-10-27 16:35:33', '2022-10-27 16:36:31');
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-- 1. 查询 姓名 为 杨逍 的员工
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select * from tb_emp where name = '杨逍';
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-- 2. 查询在 id小于等于5 的员工信息
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select * from tb_emp where id <= 5;
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-- 3. 查询 没有分配职位 的员工信息 -- 判断 null , 用 is null
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select * from tb_emp where job is null;
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-- 4. 查询 有职位 的员工信息 -- 判断 不是null , 用 is not null
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select * from tb_emp where job is not null;
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-- 5. 查询 密码不等于 '123456' 的员工信息
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select * from tb_emp where password != '123456';
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select * from tb_emp where password <> '123456';
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-- 6. 查询入职日期 在 '2000-01-01' (包含) 到 '2010-01-01'(包含) 之间的员工信息
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select * from tb_emp where entrydate >= '2000-01-01' and entrydate <= '2010-01-01';
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select * from tb_emp where entrydate between '2000-01-01' and '2010-01-01';
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-- 7. 查询 入职时间 在 '2000-01-01' (包含) 到 '2010-01-01'(包含) 之间 且 性别为女 的员工信息
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select * from tb_emp where entrydate between '2000-01-01' and '2010-01-01' and gender = 2;
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-- 8. 查询 职位是 2 (讲师), 3 (学工主管), 4 (教研主管) 的员工信息
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select * from tb_emp where job = 2 or job = 3 or job = 4;
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select * from tb_emp where job in (2,3,4);
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-- 9. 查询姓名为两个字的员工信息 【_匹配一个字符 %匹配0或多个字符】
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select * from tb_emp where name like '__';
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-- 10. 查询姓 '张' 的员工信息
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select * from tb_emp where name like '张%';
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-- 11. 查询姓名中包含 '三' 的员工信息
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select * from tb_emp where name like '%三%';
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-- 练习 : 员工管理列表查询
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-- 条件 : name , gender , entrydate
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select * from tb_emp where name like '%张%'
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and gender = 1
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and entrydate between '2000-01-01' and '2010-01-01';
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-- 分组查询---聚合函数
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-- 1. 统计该企业员工数量 -- count
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-- count(字段)
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select count(id) from tb_emp;
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select count(name) from tb_emp;
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select count(job) from tb_emp; -- 注意：所有的聚合函数是排除null计算的！！！！
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select count(*) from tb_emp;
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select count(0) from tb_emp;-- 统计总数推荐count(0)
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-- 2. 统计该企业最早入职的员工的入职日期
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select min(entrydate) from tb_emp;
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-- 3. 统计该企业最近入职的员工的入职日期
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select max(entrydate) from tb_emp;
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-- 4. 统计该企业员工的 ID 之和
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select sum(id) from tb_emp;
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-- 5. 统计该企业员工 ID 的平均值
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select avg(id) from tb_emp;
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-- 6. 不用avg如何计算平均值
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select sum(id)/count(0) from tb_emp;
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-- 分组查询
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-- 1. 根据性别分组 , 统计男性和女性员工的数量 -- count(*)
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-- 注意：分组之后能查询的字段只能是分组字段或者聚合函数才有意义
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select gender, count(1) from tb_emp group by gender;
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-- 2. 先查询入职时间在 '2015-01-01' (包含) 以前的员工 , 并对结果根据职位分组 , 获取员工数量大于等于2的职位 -- count
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select job,count(0) from tb_emp
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where entrydate <= '2015-01-01'
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group by job
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having count(0)>= 2;
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