DROP TABLE IF EXISTS `liuyan`; CREATE TABLE `liuyan` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(32) NOT NULL, `author` varchar(16) DEFAULT NULL, `addtime` datetime DEFAULT NULL, `content` text, `isdelete` char(1) NOT NULL DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of liuyan -- ---------------------------- INSERT INTO `liuyan` VALUES ('1', '介绍', '大雄', '2017-02-14 09:59:37', '哥不是一匹好马，但也不是一头普通的毛驴', '0'); INSERT INTO `liuyan` VALUES ('2', '叮当猫', '熊熊', '2016-02-16 09:59:44', '你牙缝里有韭菜，扣出来贼哥吃', '0'); INSERT INTO `liuyan` VALUES ('3', '花花', '苗苗', '2017-05-28 09:59:52', '苗苗问花花:卖萌是褒义词还是贬义词？', '0'); INSERT INTO `liuyan` VALUES ('4', '霞哥', '大雄', '2017-08-29 09:59:57', '斗战色佛', '0'); INSERT INTO `liuyan` VALUES ('5', '晨晨', '逗比', '2010-06-22 10:00:03', '你笑起来像一朵菊花,菊花残，man腚伤', '0');
1.创建留言数据库: liuyandb;
结果：
2.在liuyandb数据库中创建留言表liuyan，结构如下:
|
表名 |
liuyan |
留言信息表 |
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序号 |
字段名称 |
字段说明 |
类型 |
属性 |
备注 |
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1 |
id |
编号 |
int |
非空 |
主键,自增1 |
|
2 |
title |
标题 |
varchar(32) |
非空 |
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3 |
author |
作者 |
varchar(16) |
可以空 |
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4 |
addtime |
留言时间 |
datetime |
非空 |
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5 |
content |
留言内容 |
text |
非空 |
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6 |
isdelete |
是否删除 |
char(1) |
非空 |
默认值 0 |
结果：
3.在留言表最后添加一列状态（status char(1) 默认值为0）
alter table liuyan change STATUS status char(1)
4.修改留言表author的默认值为’youku’,设为非空
alter table liuyan modify author varchar(50) default 'youku' not null;
5.删除liuyan表中的isdelete字段
alter table liuyan drop isdelete;
6.为留言表添加>5条测试数据 (例如:)
INSERT INTO `liuyan` VALUES ('6', '标表题', '大mao', '2017-06-14 09:59:37', 'h', '0');
INSERT INTO `liuyan` VALUES ('7', 'OOOO', 'ange好吗', '2016-04-16 09:59:44', '猪', '0');
INSERT INTO `liuyan` VALUES ('8', 'ME', '刚刚', '2017-02-28 09:59:52', '楼主十足', '0');
INSERT INTO `liuyan` VALUES ('9', 'IW', '卡卡', '2017-06-29 09:59:57', '万岁', '0');
INSERT INTO `liuyan` VALUES ('10', 'WHO', '姑奶奶', '2010-24-22 10:00:03', '赞赞赞', '0');
7. 要求将id值大于3的信息中author 字段值改为admin
update liuyan set author = 'admin' where id > 3;
8. 删除id号为4的数据。
delete from liuyan where id=4;
附加题：
- 为留言表添加>10条测试数据，要求分三个作者添加数据
- 查询某一个作者的留言信息。
- 查询所有数据，按时间降序排序。
- 获取id在2到6之间的留言信息，并按时间降序排序
- 统计每个作者留了多少条留言，并对数量按从小到大排序。
- 将id为8、9的两条数据的作者改为’doudou’.
- 取出最新的三条留言。
- 查询留言者中包含”a”字母的留言信息，并按留言时间从小到大排序
- 删除”作者”重复的数据,并保留id最大的一个作者
MySQL 练习题2
1.表关系
2.下面:开始你的表演
1.查询所有人员信息
DROP TABLE IF EXISTS `ren`; CREATE TABLE `ren` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(32) NOT NULL, `age` int(8) DEFAULT NULL, `salary` int(8) DEFAULT NULL, `leader` int(11) NOT NULL DEFAULT '0', `menpai` char(50) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of liuyan -- ---------------------------- INSERT INTO `liuyan` VALUES ('1', '张丰', '100', '10000', '0', '武当'); INSERT INTO `liuyan` VALUES ('2', '张无忌', '20', '8000', '0', '明教'); INSERT INTO `liuyan` VALUES ('3', '岳不群', '40', '6500', '0', '华山'); INSERT INTO `liuyan` VALUES ('4', '东方不败', '35', '12000', '0', '日月神教'); INSERT INTO `liuyan` VALUES ('5', '令狐冲', '21', '4000', '3', '华山'); INSERT INTO `liuyan` VALUES ('6', '林平芝', '18', '2000', '3', '华山'); INSERT INTO `liuyan` VALUES ('7', '金毛狮王', '50', '10000', '2', '明教'); INSERT INTO `liuyan` VALUES ('8', '张翠山', '46', '10000', '1', '武当'); INSERT INTO `liuyan` VALUES ('9', '张远桥', '55', '6500', '1', '武当'); INSERT INTO `liuyan` VALUES ('10', 'Alex', '12', '350', '0', 'python');
2.只查询人员的姓名和年龄
select name,age from ren;
3.查询年龄为20岁的有哪些人员
select name from ren where age=20;
4.查询60岁以下的人员有哪些人员
select name from ren where age<60;
5.查询50岁以上并且工资大于8000的人员有哪些
select name from ren where age>50 and salary>8000;
6.查询姓[张]的人员有哪些
select * from ren where name like '张%';
7.查询哪些人员属于 武当/华山/嵩山#没有嵩山
select * from ren where menpai in('武当','华山')
8.查询工资在 5000-8900 的人员有哪些
select * from ren where salary between 5000 and 8900;
9.查询所有人员,要求按工资倒序排列
select * from ren order by salary desc;
10.查询令狐冲的领导人是谁
select * from ren where menpai=(select menpai from ren where name = '令狐冲') and leader='0';
11.查询人员表中最高工资是多少
select max(salary) from ren;
12.查询人员表中最低工资是多少
-- 12.查询人员表中最低工资是多少
select min(salary) from ren;
13.查询所有人员的平均工资是多少
select AVG(salary) from ren;
14.查询所有人员的工资总和是多少
select sum(salary) from ren;
15.查询目前有多少个人员
select count(name) from ren;
16.查询当前武林中有哪些门派
方式一：select menpai from ren group by menpai;
方式二：select DISTINCT menpai from ren;
17.查询 武当派 最高工资是谁
select name from ren where menpai='武当' and salary=(select max(salary) from ren where menpai='武当');
18.查询各门派的平均工资是多少
select avg(salary),menpai from ren group by menpai;
19.查询当前武林中有哪些门派的平均工资大于8000 并按工资倒序排列
elect avg(salary),menpai from ren group by menpai having avg(salary)>8000 order by avg(salary) desc;
20.查询当前人员表的中的第3条数据到第7条数据
select * from ren LIMIT 2,5;
21.查询哪些门派下没有弟子
select * from ren group by menpai having count(*) =1;
22.查询武当派下有哪些弟子
select * from ren where menpai='武当' and leader != 0;
23.查询各门派的工资总和按倒序/正序排列
倒序：select menpai,sum(salary) from ren group by menpai order by sum(salary) desc;
24.删除工资重复的人员,请保留年龄最大的一个人
25.将武当派 张三丰 修改为 张丰
update ren set name ='张丰' where name='张三丰';
26.将所有门派大哥工资上调10%,但不包括Alex.
update ren set salary = salary+salary*0.1 where leader = 0 and name !='Alex';
27.查看哪些人员的门派已登记地理位置.
select name,address from ren,dept where dept.dname = ren.menpai;
28.查询所有人员门派的位置信息,不存在位置信息则不显示
SELECT name,address FROM ren LEFT JOIN dept on ren.menpai = dept.dname;
29.在湖北省内的门派中的人员有哪些.
SELECT * FROM ren INNER JOIN dept on ren.menpai = dept.dname AND dept.address = '湖北';
30.在陕西省内门派中的工资小于5000,年龄大于20岁的人员有哪些,按主键倒序排列
SELECT * FROM ren INNER JOIN dept on ren.menpai = dept.dname
AND dept.address = '陕西' and ren.salary <5000 AND ren.age >20 ORDER BY ren.id DESC;
MySQL 练习题3
1.创建表结构和表数据
-- 创建数据表 CREATE TABLE IF NOT EXISTS tdb_goods( goods_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT, -- 商品主键 goods_name VARCHAR(150) NOT NULL, -- 商品名称 goods_cate VARCHAR(40) NOT NULL, -- 商品类型 brand_name VARCHAR(40) NOT NULL, -- 商品品牌 goods_price DECIMAL(15,3) UNSIGNED NOT NULL DEFAULT 0, -- 商品价格 is_show BOOLEAN NOT NULL DEFAULT 1, -- 是否上架 is_saleoff BOOLEAN NOT NULL DEFAULT 0 -- 是否打折 ); -- 写入记录 INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('R510VC 15.6英寸笔记本','笔记本','华硕','3399',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Y400N 14.0英寸笔记本电脑','笔记本','联想','4899',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('G150TH 15.6英寸游戏本','游戏本','雷神','8499',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X550CC 15.6英寸笔记本','笔记本','华硕','2799',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X240(20ALA0EYCD) 12.5英寸超极本','超级本','联想','4999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('U330P 13.3英寸超极本','超级本','联想','4299',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('SVP13226SCB 13.3英寸触控超极本','超级本','索尼','7999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iPad mini MD531CH/A 7.9英寸平板电脑','平板电脑','苹果','1998',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版）','平板电脑','苹果','3388',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版）','平板电脑','苹果','2788',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('IdeaCentre C340 20英寸一体电脑 ','台式机','联想','3499',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Vostro 3800-R1206 台式电脑','台式机','戴尔','2899',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iMac ME086CH/A 21.5英寸一体电脑','台式机','苹果','9188',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ）','台式机','宏碁','3699',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Z220SFF F4F06PA工作站','服务器/工作站','惠普','4288',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('PowerEdge T110 II服务器','服务器/工作站','戴尔','5388',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Mac Pro MD878CH/A 专业级台式电脑','服务器/工作站','苹果','28888',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' HMZ-T3W 头戴显示设备','笔记本配件','索尼','6999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('商务双肩背包','笔记本配件','索尼','99',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X3250 M4机架式服务器 2583i14','服务器/工作站','IBM','6888',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('玄龙精英版 笔记本散热器','笔记本配件','九州风神','',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' HMZ-T3W 头戴显示设备','笔记本配件','索尼','6999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('商务双肩背包','笔记本配件','索尼','99',DEFAULT,DEFAULT); 创建表和数据
2. 求所有电脑产品的平均价格,并且保留两位小数，AVG,MAX,MIN,COUNT,SUM为聚合函数
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SELECT ROUND(AVG(goods_price),2) AS avg_price FROM tdb_goods;
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3.查询所有价格大于平均价格的商品，并且按价格降序排序
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SELECT goods_id,goods_name,goods_price FROM tdb_goods
WHERE goods_price > (SELECT ROUND(AVG(goods_price),2) AS avg_price FROM tdb_goods)
ORDER BY goods_price DESC;
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4.查询类型为“超记本”的商品价格
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SELECT goods_price FROM tdb_goods WHERE goods_cate = '超级本';
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5.查询价格等于"超级本"价格的商品，并且按价格降序排列
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SELECT goods_id,goods_name,goods_price FROM tdb_goods
WHERE goods_price IN (SELECT goods_price FROM tdb_goods WHERE goods_cate = '超级本')
ORDER BY goods_price DESC;
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6.创建“商品类别”表
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CREATE TABLE IF NOT EXISTS tdb_goods_cates(
cate_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
cate_name VARCHAR(40)
);
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7.查询tdb_goods表的类别记录，并且按"类别"分组
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SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;
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8.将分组结果写入到tdb_goods_cates数据表
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INSERT tdb_goods_cates (cate_name) SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;
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9.通过tdb_goods_cates数据表来更新tdb_goods表中的'类别字段'
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-- 1.通过内连接得到两个表的结果select * from tdb_goods INNER JOIN tdb_goods_cates ON goods_cate = cate_name;
-- 2.通过上面的得到的临时表进行 类别字段更新UPDATE tdb_goods INNER JOIN tdb_goods_cates ON goods_cate = cate_name
SET goods_cate = cate_id;
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10.通过CREATE...SELECT来 创建[品牌]表 并且同时写入记录
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-- 1.获得品牌名称SELECT brand_name FROM tdb_goods GROUP BY brand_name;
-- 2.创建品牌表,并且插入品牌数据 CREATE TABLE tdb_goods_brands (
brand_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
brand_name VARCHAR(40) NOT NULL
) SELECT brand_name FROM tdb_goods GROUP BY brand_name;
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11.通过tdb_goods_brands 品牌表 来更新 tdb_goods商品表
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-- 错误<br>UPDATE tdb_goods INNER JOIN tdb_goods_brands ON brand_name = brand_nameSET brand_name = brand_id;
-- Column 'brand_name' in field list is ambigous-- 正确UPDATE tdb_goods AS g INNER JOIN tdb_goods_brands AS b ON g.brand_name = b.brand_name
SET g.brand_name = b.brand_id;
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12.查看tdb_goods的数据表结构
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DESC tdb_goods;
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13.通过ALTER TABLE语句修改商品表结构,goods_cate更新为cate_id, brand_name更新为brand_id
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ALTER TABLE tdb_goods
CHANGE goods_cate cate_id SMALLINT NOT NULL,
CHANGE brand_name brand_id SMALLINT NOT NULL;
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14.分别在tdb_goods_cates(类别表)和tdb_goods_brands(品牌表)插入记录
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INSERT tdb_goods_cates(cate_name) VALUES('路由器'),('交换机'),('网卡');
INSERT tdb_goods_brands(brand_name) VALUES('海尔'),('清华同方'),('神舟');
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15.在tdb_goods数据表写入任意记录
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INSERT tdb_goods(goods_name,cate_id,brand_id,goods_price) VALUES('LaserJet Pro P1606dn 黑白激光打印机','12','4','1849');
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16.查询所有商品的详细信息(通过内连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
INNER JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
INNER JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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17.查询所有商品的详细信息(通过左外连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
LEFT JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
LEFT JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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18.查询所有商品的详细信息(通过右外连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
RIGHT JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
RIGHT JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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19.无限分类的数据表设计
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CREATE TABLE tdb_goods_types(
type_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
type_name VARCHAR(20) NOT NULL,
parent_id SMALLINT UNSIGNED NOT NULL DEFAULT 0
); INSERT tdb_goods_types(type_name,parent_id) VALUES('家用电器',DEFAULT);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑、办公',DEFAULT);
INSERT tdb_goods_types(type_name,parent_id) VALUES('大家电',1);
INSERT tdb_goods_types(type_name,parent_id) VALUES('生活电器',1);
INSERT tdb_goods_types(type_name,parent_id) VALUES('平板电视',3);
INSERT tdb_goods_types(type_name,parent_id) VALUES('空调',3);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电风扇',4);
INSERT tdb_goods_types(type_name,parent_id) VALUES('饮水机',4);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑整机',2);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑配件',2);
INSERT tdb_goods_types(type_name,parent_id) VALUES('笔记本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('超级本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('游戏本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('CPU',10);
INSERT tdb_goods_types(type_name,parent_id) VALUES('主机',10);
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20.查找所有分类及其父类(将自身作为临时表使用)
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select * FROM tdb_goods_types p1;
select * FROM tdb_goods_types p2;
SELECT p1.type_id,p1.type_name,p2.type_name as '父类'
FROM tdb_goods_types p1 LEFT JOIN tdb_goods_types p2
on p1.parent_id = p2.type_id
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21. 复制编号为12,20的两条记录
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SELECT * FROM tdb_goods WHERE goods_id IN (19,20);
-- INSERT ... SELECT实现复制 INSERT tdb_goods(goods_name,cate_id,brand_id) SELECT goods_name,cate_id,brand_id FROM tdb_goods WHERE goods_id IN (19,20);
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22.查找重复记录
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SELECT goods_id,goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2;
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23. 删除重复记录
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#方式一: 1.查询重复记录,获得重复字段
SELECT goods_name FROM tdb_goods ROUP BY goods_name HAVING count(goods_name) >= 2
2.通过重复字段进行删除
-- 错误
DELETE FROM tdb_goods WHERE goods_name in(SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)
-- [Err] 1093 - You can't specify target table 'tdb_goods' for update in FROM clause
-- 不能在同一个表中即查询数据又删除数据
-- 正确
DELETE FROM tdb_goods WHERE goods_name in(SELECT * from (SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as 别名)
注意: 使用临时表 将子查询包裹,并起个别名
#方式二:保留一条 DELETE FROM tdb_goods WHERE goods_name in(SELECT * from (SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as ss)
and goods_id not in(SELECT * from (SELECT goods_id FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as 别名)
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DROP TABLE IF EXISTS `liuyan`; CREATE TABLE `liuyan` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(32) NOT NULL, `author` varchar(16) DEFAULT NULL, `addtime` datetime DEFAULT NULL, `content` text, `isdelete` char(1) NOT NULL DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of liuyan -- ---------------------------- INSERT INTO `liuyan` VALUES ('1', '介绍', '大雄', '2017-02-14 09:59:37', '哥不是一匹好马，但也不是一头普通的毛驴', '0'); INSERT INTO `liuyan` VALUES ('2', '叮当猫', '熊熊', '2016-02-16 09:59:44', '你牙缝里有韭菜，扣出来贼哥吃', '0'); INSERT INTO `liuyan` VALUES ('3', '花花', '苗苗', '2017-05-28 09:59:52', '苗苗问花花:卖萌是褒义词还是贬义词？', '0'); INSERT INTO `liuyan` VALUES ('4', '霞哥', '大雄', '2017-08-29 09:59:57', '斗战色佛', '0'); INSERT INTO `liuyan` VALUES ('5', '晨晨', '逗比', '2010-06-22 10:00:03', '你笑起来像一朵菊花,菊花残，man腚伤', '0');
1.创建留言数据库: liuyandb;
结果：
2.在liuyandb数据库中创建留言表liuyan，结构如下:
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表名 |
liuyan |
留言信息表 |
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序号 |
字段名称 |
字段说明 |
类型 |
属性 |
备注 |
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1 |
id |
编号 |
int |
非空 |
主键,自增1 |
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2 |
title |
标题 |
varchar(32) |
非空 |
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3 |
author |
作者 |
varchar(16) |
可以空 |
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4 |
addtime |
留言时间 |
datetime |
非空 |
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5 |
content |
留言内容 |
text |
非空 |
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6 |
isdelete |
是否删除 |
char(1) |
非空 |
默认值 0 |
结果：
3.在留言表最后添加一列状态（status char(1) 默认值为0）
alter table liuyan change STATUS status char(1)
4.修改留言表author的默认值为’youku’,设为非空
alter table liuyan modify author varchar(50) default 'youku' not null;
5.删除liuyan表中的isdelete字段
alter table liuyan drop isdelete;
6.为留言表添加>5条测试数据 (例如:)
INSERT INTO `liuyan` VALUES ('6', '标表题', '大mao', '2017-06-14 09:59:37', 'h', '0');
INSERT INTO `liuyan` VALUES ('7', 'OOOO', 'ange好吗', '2016-04-16 09:59:44', '猪', '0');
INSERT INTO `liuyan` VALUES ('8', 'ME', '刚刚', '2017-02-28 09:59:52', '楼主十足', '0');
INSERT INTO `liuyan` VALUES ('9', 'IW', '卡卡', '2017-06-29 09:59:57', '万岁', '0');
INSERT INTO `liuyan` VALUES ('10', 'WHO', '姑奶奶', '2010-24-22 10:00:03', '赞赞赞', '0');
7. 要求将id值大于3的信息中author 字段值改为admin
update liuyan set author = 'admin' where id > 3;
8. 删除id号为4的数据。
delete from liuyan where id=4;
附加题：
- 为留言表添加>10条测试数据，要求分三个作者添加数据
- 查询某一个作者的留言信息。
- 查询所有数据，按时间降序排序。
- 获取id在2到6之间的留言信息，并按时间降序排序
- 统计每个作者留了多少条留言，并对数量按从小到大排序。
- 将id为8、9的两条数据的作者改为’doudou’.
- 取出最新的三条留言。
- 查询留言者中包含”a”字母的留言信息，并按留言时间从小到大排序
- 删除”作者”重复的数据,并保留id最大的一个作者
MySQL 练习题2
1.表关系
2.下面:开始你的表演
1.查询所有人员信息
DROP TABLE IF EXISTS `ren`; CREATE TABLE `ren` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(32) NOT NULL, `age` int(8) DEFAULT NULL, `salary` int(8) DEFAULT NULL, `leader` int(11) NOT NULL DEFAULT '0', `menpai` char(50) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of liuyan -- ---------------------------- INSERT INTO `liuyan` VALUES ('1', '张丰', '100', '10000', '0', '武当'); INSERT INTO `liuyan` VALUES ('2', '张无忌', '20', '8000', '0', '明教'); INSERT INTO `liuyan` VALUES ('3', '岳不群', '40', '6500', '0', '华山'); INSERT INTO `liuyan` VALUES ('4', '东方不败', '35', '12000', '0', '日月神教'); INSERT INTO `liuyan` VALUES ('5', '令狐冲', '21', '4000', '3', '华山'); INSERT INTO `liuyan` VALUES ('6', '林平芝', '18', '2000', '3', '华山'); INSERT INTO `liuyan` VALUES ('7', '金毛狮王', '50', '10000', '2', '明教'); INSERT INTO `liuyan` VALUES ('8', '张翠山', '46', '10000', '1', '武当'); INSERT INTO `liuyan` VALUES ('9', '张远桥', '55', '6500', '1', '武当'); INSERT INTO `liuyan` VALUES ('10', 'Alex', '12', '350', '0', 'python');
2.只查询人员的姓名和年龄
select name,age from ren;
3.查询年龄为20岁的有哪些人员
select name from ren where age=20;
4.查询60岁以下的人员有哪些人员
select name from ren where age<60;
5.查询50岁以上并且工资大于8000的人员有哪些
select name from ren where age>50 and salary>8000;
6.查询姓[张]的人员有哪些
select * from ren where name like '张%';
7.查询哪些人员属于 武当/华山/嵩山#没有嵩山
select * from ren where menpai in('武当','华山')
8.查询工资在 5000-8900 的人员有哪些
select * from ren where salary between 5000 and 8900;
9.查询所有人员,要求按工资倒序排列
select * from ren order by salary desc;
10.查询令狐冲的领导人是谁
select * from ren where menpai=(select menpai from ren where name = '令狐冲') and leader='0';
11.查询人员表中最高工资是多少
select max(salary) from ren;
12.查询人员表中最低工资是多少
-- 12.查询人员表中最低工资是多少
select min(salary) from ren;
13.查询所有人员的平均工资是多少
select AVG(salary) from ren;
14.查询所有人员的工资总和是多少
select sum(salary) from ren;
15.查询目前有多少个人员
select count(name) from ren;
16.查询当前武林中有哪些门派
方式一：select menpai from ren group by menpai;
方式二：select DISTINCT menpai from ren;
17.查询 武当派 最高工资是谁
select name from ren where menpai='武当' and salary=(select max(salary) from ren where menpai='武当');
18.查询各门派的平均工资是多少
select avg(salary),menpai from ren group by menpai;
19.查询当前武林中有哪些门派的平均工资大于8000 并按工资倒序排列
elect avg(salary),menpai from ren group by menpai having avg(salary)>8000 order by avg(salary) desc;
20.查询当前人员表的中的第3条数据到第7条数据
select * from ren LIMIT 2,5;
21.查询哪些门派下没有弟子
select * from ren group by menpai having count(*) =1;
22.查询武当派下有哪些弟子
select * from ren where menpai='武当' and leader != 0;
23.查询各门派的工资总和按倒序/正序排列
倒序：select menpai,sum(salary) from ren group by menpai order by sum(salary) desc;
24.删除工资重复的人员,请保留年龄最大的一个人
25.将武当派 张三丰 修改为 张丰
update ren set name ='张丰' where name='张三丰';
26.将所有门派大哥工资上调10%,但不包括Alex.
update ren set salary = salary+salary*0.1 where leader = 0 and name !='Alex';
27.查看哪些人员的门派已登记地理位置.
select name,address from ren,dept where dept.dname = ren.menpai;
28.查询所有人员门派的位置信息,不存在位置信息则不显示
SELECT name,address FROM ren LEFT JOIN dept on ren.menpai = dept.dname;
29.在湖北省内的门派中的人员有哪些.
SELECT * FROM ren INNER JOIN dept on ren.menpai = dept.dname AND dept.address = '湖北';
30.在陕西省内门派中的工资小于5000,年龄大于20岁的人员有哪些,按主键倒序排列
SELECT * FROM ren INNER JOIN dept on ren.menpai = dept.dname
AND dept.address = '陕西' and ren.salary <5000 AND ren.age >20 ORDER BY ren.id DESC;
MySQL 练习题3
1.创建表结构和表数据
-- 创建数据表 CREATE TABLE IF NOT EXISTS tdb_goods( goods_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT, -- 商品主键 goods_name VARCHAR(150) NOT NULL, -- 商品名称 goods_cate VARCHAR(40) NOT NULL, -- 商品类型 brand_name VARCHAR(40) NOT NULL, -- 商品品牌 goods_price DECIMAL(15,3) UNSIGNED NOT NULL DEFAULT 0, -- 商品价格 is_show BOOLEAN NOT NULL DEFAULT 1, -- 是否上架 is_saleoff BOOLEAN NOT NULL DEFAULT 0 -- 是否打折 ); -- 写入记录 INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('R510VC 15.6英寸笔记本','笔记本','华硕','3399',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Y400N 14.0英寸笔记本电脑','笔记本','联想','4899',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('G150TH 15.6英寸游戏本','游戏本','雷神','8499',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X550CC 15.6英寸笔记本','笔记本','华硕','2799',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X240(20ALA0EYCD) 12.5英寸超极本','超级本','联想','4999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('U330P 13.3英寸超极本','超级本','联想','4299',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('SVP13226SCB 13.3英寸触控超极本','超级本','索尼','7999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iPad mini MD531CH/A 7.9英寸平板电脑','平板电脑','苹果','1998',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版）','平板电脑','苹果','3388',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版）','平板电脑','苹果','2788',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('IdeaCentre C340 20英寸一体电脑 ','台式机','联想','3499',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Vostro 3800-R1206 台式电脑','台式机','戴尔','2899',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('iMac ME086CH/A 21.5英寸一体电脑','台式机','苹果','9188',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ）','台式机','宏碁','3699',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Z220SFF F4F06PA工作站','服务器/工作站','惠普','4288',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('PowerEdge T110 II服务器','服务器/工作站','戴尔','5388',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('Mac Pro MD878CH/A 专业级台式电脑','服务器/工作站','苹果','28888',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' HMZ-T3W 头戴显示设备','笔记本配件','索尼','6999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('商务双肩背包','笔记本配件','索尼','99',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('X3250 M4机架式服务器 2583i14','服务器/工作站','IBM','6888',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('玄龙精英版 笔记本散热器','笔记本配件','九州风神','',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES(' HMZ-T3W 头戴显示设备','笔记本配件','索尼','6999',DEFAULT,DEFAULT); INSERT tdb_goods (goods_name,goods_cate,brand_name,goods_price,is_show,is_saleoff) VALUES('商务双肩背包','笔记本配件','索尼','99',DEFAULT,DEFAULT); 创建表和数据
2. 求所有电脑产品的平均价格,并且保留两位小数，AVG,MAX,MIN,COUNT,SUM为聚合函数
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SELECT ROUND(AVG(goods_price),2) AS avg_price FROM tdb_goods;
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3.查询所有价格大于平均价格的商品，并且按价格降序排序
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SELECT goods_id,goods_name,goods_price FROM tdb_goods
WHERE goods_price > (SELECT ROUND(AVG(goods_price),2) AS avg_price FROM tdb_goods)
ORDER BY goods_price DESC;
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4.查询类型为“超记本”的商品价格
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SELECT goods_price FROM tdb_goods WHERE goods_cate = '超级本';
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5.查询价格等于"超级本"价格的商品，并且按价格降序排列
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SELECT goods_id,goods_name,goods_price FROM tdb_goods
WHERE goods_price IN (SELECT goods_price FROM tdb_goods WHERE goods_cate = '超级本')
ORDER BY goods_price DESC;
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6.创建“商品类别”表
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CREATE TABLE IF NOT EXISTS tdb_goods_cates(
cate_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
cate_name VARCHAR(40)
);
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7.查询tdb_goods表的类别记录，并且按"类别"分组
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SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;
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8.将分组结果写入到tdb_goods_cates数据表
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INSERT tdb_goods_cates (cate_name) SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;
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9.通过tdb_goods_cates数据表来更新tdb_goods表中的'类别字段'
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-- 1.通过内连接得到两个表的结果select * from tdb_goods INNER JOIN tdb_goods_cates ON goods_cate = cate_name;
-- 2.通过上面的得到的临时表进行 类别字段更新UPDATE tdb_goods INNER JOIN tdb_goods_cates ON goods_cate = cate_name
SET goods_cate = cate_id;
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10.通过CREATE...SELECT来 创建[品牌]表 并且同时写入记录
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-- 1.获得品牌名称SELECT brand_name FROM tdb_goods GROUP BY brand_name;
-- 2.创建品牌表,并且插入品牌数据 CREATE TABLE tdb_goods_brands (
brand_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
brand_name VARCHAR(40) NOT NULL
) SELECT brand_name FROM tdb_goods GROUP BY brand_name;
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11.通过tdb_goods_brands 品牌表 来更新 tdb_goods商品表
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-- 错误<br>UPDATE tdb_goods INNER JOIN tdb_goods_brands ON brand_name = brand_nameSET brand_name = brand_id;
-- Column 'brand_name' in field list is ambigous-- 正确UPDATE tdb_goods AS g INNER JOIN tdb_goods_brands AS b ON g.brand_name = b.brand_name
SET g.brand_name = b.brand_id;
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12.查看tdb_goods的数据表结构
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DESC tdb_goods;
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13.通过ALTER TABLE语句修改商品表结构,goods_cate更新为cate_id, brand_name更新为brand_id
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ALTER TABLE tdb_goods
CHANGE goods_cate cate_id SMALLINT NOT NULL,
CHANGE brand_name brand_id SMALLINT NOT NULL;
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14.分别在tdb_goods_cates(类别表)和tdb_goods_brands(品牌表)插入记录
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INSERT tdb_goods_cates(cate_name) VALUES('路由器'),('交换机'),('网卡');
INSERT tdb_goods_brands(brand_name) VALUES('海尔'),('清华同方'),('神舟');
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15.在tdb_goods数据表写入任意记录
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INSERT tdb_goods(goods_name,cate_id,brand_id,goods_price) VALUES('LaserJet Pro P1606dn 黑白激光打印机','12','4','1849');
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16.查询所有商品的详细信息(通过内连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
INNER JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
INNER JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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17.查询所有商品的详细信息(通过左外连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
LEFT JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
LEFT JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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18.查询所有商品的详细信息(通过右外连接实现)
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SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g
RIGHT JOIN tdb_goods_cates AS c ON g.cate_id = c.cate_id
RIGHT JOIN tdb_goods_brands AS b ON g.brand_id = b.brand_id;
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19.无限分类的数据表设计
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CREATE TABLE tdb_goods_types(
type_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
type_name VARCHAR(20) NOT NULL,
parent_id SMALLINT UNSIGNED NOT NULL DEFAULT 0
); INSERT tdb_goods_types(type_name,parent_id) VALUES('家用电器',DEFAULT);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑、办公',DEFAULT);
INSERT tdb_goods_types(type_name,parent_id) VALUES('大家电',1);
INSERT tdb_goods_types(type_name,parent_id) VALUES('生活电器',1);
INSERT tdb_goods_types(type_name,parent_id) VALUES('平板电视',3);
INSERT tdb_goods_types(type_name,parent_id) VALUES('空调',3);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电风扇',4);
INSERT tdb_goods_types(type_name,parent_id) VALUES('饮水机',4);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑整机',2);
INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑配件',2);
INSERT tdb_goods_types(type_name,parent_id) VALUES('笔记本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('超级本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('游戏本',9);
INSERT tdb_goods_types(type_name,parent_id) VALUES('CPU',10);
INSERT tdb_goods_types(type_name,parent_id) VALUES('主机',10);
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20.查找所有分类及其父类(将自身作为临时表使用)
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select * FROM tdb_goods_types p1;
select * FROM tdb_goods_types p2;
SELECT p1.type_id,p1.type_name,p2.type_name as '父类'
FROM tdb_goods_types p1 LEFT JOIN tdb_goods_types p2
on p1.parent_id = p2.type_id
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21. 复制编号为12,20的两条记录
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SELECT * FROM tdb_goods WHERE goods_id IN (19,20);
-- INSERT ... SELECT实现复制 INSERT tdb_goods(goods_name,cate_id,brand_id) SELECT goods_name,cate_id,brand_id FROM tdb_goods WHERE goods_id IN (19,20);
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22.查找重复记录
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SELECT goods_id,goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2;
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23. 删除重复记录
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#方式一: 1.查询重复记录,获得重复字段
SELECT goods_name FROM tdb_goods ROUP BY goods_name HAVING count(goods_name) >= 2
2.通过重复字段进行删除
-- 错误
DELETE FROM tdb_goods WHERE goods_name in(SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)
-- [Err] 1093 - You can't specify target table 'tdb_goods' for update in FROM clause
-- 不能在同一个表中即查询数据又删除数据
-- 正确
DELETE FROM tdb_goods WHERE goods_name in(SELECT * from (SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as 别名)
注意: 使用临时表 将子查询包裹,并起个别名
#方式二:保留一条 DELETE FROM tdb_goods WHERE goods_name in(SELECT * from (SELECT goods_name FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as ss)
and goods_id not in(SELECT * from (SELECT goods_id FROM tdb_goods
GROUP BY goods_name HAVING count(goods_name) >= 2)as 别名)
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