商品数据管理与SQL实战
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);
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; |
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; |
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'; |
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; |
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) ); |
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; |
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; |
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; |
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; |
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_nameSET g.brand_name = b.brand_id; |
12.查看tdb_goods的数据表结构
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DESC tdb_goods; |
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; |
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'); |
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'); |
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; |
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; |
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; |
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); |
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 p2on p1.parent_id = p2.type_id |
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); |
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; |
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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