MySQL基础五：子查询与链接_MySQL
| 本篇文章参考：http://www.imooc.com/learn/122 首先下载好数据，网址上面有； #首先录入数据：CREATE TABLE IF NOT EXISTS tdb_goods( goods_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT, goods_name VARCHAR(150) NOT NULL, goods_cate VARCHAR(40) NOT NULL, brand_name VARCHAR(40) NOT NULL, goods_price DECIMAL(15,3) UNSIGNED NOT NULL DEFAULT 0, is_show BOOLEAN NOT NULL DEFAULT 1, is_saleoff BOOLEAN NOT NULL DEFAULT 0 );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);#查看数据表；mysql>mysql> SHOW TABLES;+-----------------+| Tables_in_world |+-----------------+| city || country || countrylanguage || provinces || tdb_goods || test || users |+-----------------+7 rows in set (0.00 sec)mysql> SHOW COLUMNS FROM tdb_goods;+-------------+------------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-------------+------------------------+------+-----+---------+----------------+| goods_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || goods_name | varchar(150) | NO | | NULL | || goods_cate | varchar(40) | NO | | NULL | || brand_name | varchar(40) | NO | | NULL | || goods_price | decimal(15,3) unsigned | NO | | 0.000 | || is_show | tinyint(1) | NO | | 1 | || is_saleoff | tinyint(1) | NO | | 0 | |+-------------+------------------------+------+-----+---------+----------------+7 rows in set (0.01 sec)mysql> SELECT * FROM tdb_goods/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 goods_cate: 笔记本 brand_name: 华硕goods_price: 3399.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 goods_cate: 笔记本 brand_name: 联想goods_price: 4899.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 goods_cate: 游戏本 brand_name: 雷神goods_price: 8499.000 is_show: 1 is_saleoff: 0*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 goods_cate: 笔记本 brand_name: 华硕goods_price: 2799.000 is_show: 1 is_saleoff: 0*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 goods_cate: 超级本 brand_name: 联想goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 goods_cate: 超级本 brand_name: 联想goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 goods_cate: 超级本 brand_name: 索尼goods_price: 7999.000 is_show: 1 is_saleoff: 0*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 goods_cate: 平板电脑 brand_name: 苹果goods_price: 1998.000 is_show: 1 is_saleoff: 0*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） goods_cate: 平板电脑 brand_name: 苹果goods_price: 3388.000 is_show: 1 is_saleoff: 0*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） goods_cate: 平板电脑 brand_name: 苹果goods_price: 2788.000 is_show: 1 is_saleoff: 0*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 goods_cate: 台式机 brand_name: 联想goods_price: 3499.000 is_show: 1 is_saleoff: 0*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 goods_cate: 台式机 brand_name: 戴尔goods_price: 2899.000 is_show: 1 is_saleoff: 0*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 goods_cate: 台式机 brand_name: 苹果goods_price: 9188.000 is_show: 1 is_saleoff: 0*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） goods_cate: 台式机 brand_name: 宏碁goods_price: 3699.000 is_show: 1 is_saleoff: 0*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 goods_cate: 服务器/工作站 brand_name: 惠普goods_price: 4288.000 is_show: 1 is_saleoff: 0*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 goods_cate: 服务器/工作站 brand_name: 戴尔goods_price: 5388.000 is_show: 1 is_saleoff: 0*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 goods_cate: 服务器/工作站 brand_name: 苹果goods_price: 28888.000 is_show: 1 is_saleoff: 0*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 笔记本配件 brand_name: 索尼goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 goods_cate: 笔记本配件 brand_name: 索尼goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 goods_cate: 服务器/工作站 brand_name: IBMgoods_price: 6888.000 is_show: 1 is_saleoff: 0*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 笔记本配件 brand_name: 索尼goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 goods_cate: 笔记本配件 brand_name: 索尼goods_price: 99.000 is_show: 1 is_saleoff: 022 rows in set (0.01 sec)ERROR:No query specified子查询正文 mysql> #子查询mysql> #子查询是嵌套在查询内部的查询；mysql>mysql> #使用比较运算符的子查询；mysql> #求价格平均值；mysql> SELECT AVG(goods_price) FROM tdb_goods;mysql> SELECT AVG(goods_price) FROM tdb_goods;+------------------+| AVG(goods_price) |+------------------+| 5636.3636364 |+------------------+1 row in set (0.03 sec)mysql> #四舍五入mysql> #保留到小数点后两位； mysql> SELECT ROUND(AVG(goods_price),2) FROM tdb_goods;+---------------------------+| ROUND(AVG(goods_price),2) |+---------------------------+| 5636.36 |+---------------------------+1 row in set (0.02 sec)mysql> SELECT goods_id,goods_price FROM tdb_goods WHERE goods_price>=5636.36;+----------+-------------+| goods_id | goods_price |+----------+-------------+| 3 | 8499.000 || 7 | 7999.000 || 13 | 9188.000 || 17 | 28888.000 || 18 | 6999.000 || 20 | 6888.000 || 21 | 6999.000 |+----------+-------------+7 rows in set (0.00 sec)mysql> #通过子查询实现上式；mysql> SELECT goods_id,goods_price FROM tdb_goods WHERE goods_price>=(SELECT ROUND(AVG(goods_price),2) FROM tdb_goods);+----------+-------------+| goods_id | goods_price |+----------+-------------+| 3 | 8499.000 || 7 | 7999.000 || 13 | 9188.000 || 17 | 28888.000 || 18 | 6999.000 || 20 | 6888.000 || 21 | 6999.000 |+----------+-------------+7 rows in set (0.03 sec)mysql> SELECT goods_price FROM tdb_goods WHERE goods_cate='超级本';+-------------+| goods_price |+-------------+| 4999.000 || 4299.000 || 7999.000 |+-------------+3 rows in set (0.00 sec)mysql> SELECT * FROM tdb_goods WHERE goods_cate='超级本'/G;*************************** 1. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 goods_cate: 超级本 brand_name: 联想goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 goods_cate: 超级本 brand_name: 联想goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 goods_cate: 超级本 brand_name: 索尼goods_price: 7999.000 is_show: 1 is_saleoff: 03 rows in set (0.00 sec)ERROR:No query specifiedmysql> SELECT goods_id,goods_name,goods_price FROM tdb_goods WHERE goods_price>(SELECT goods_price FROM tdb_goods WHERE goods_cate='超级本');ERROR 1242 (21000): Subquery returns more than 1 rowmysql> #鉴于上述错误，子查询用三个关键字修饰mysql> SELECT goods_id,goods_name,goods_price FROM tdb_goods WHERE goods_price>ANY(SELECT goods_price FROM tdb_goods WHERE goods_cate='超级本');+----------+----------------------------------+-------------+| goods_id | goods_name | goods_price |+----------+----------------------------------+-------------+| 2 | Y400N 14.0英寸笔记本电脑 | 4899.000 || 3 | G150TH 15.6英寸游戏本 | 8499.000 || 5 | X240(20ALA0EYCD) 12.5英寸超极本 | 4999.000 || 7 | SVP13226SCB 13.3英寸触控超极本 | 7999.000 || 13 | iMac ME086CH/A 21.5英寸一体电脑 | 9188.000 || 16 | PowerEdge T110 II服务器 | 5388.000 || 17 | Mac Pro MD878CH/A 专业级台式电脑 | 28888.000 || 18 | HMZ-T3W 头戴显示设备 | 6999.000 || 20 | X3250 M4机架式服务器 2583i14 | 6888.000 || 21 | HMZ-T3W 头戴显示设备 | 6999.000 |+----------+----------------------------------+-------------+10 rows in set (0.00 sec)mysql> SELECT goods_id,goods_name,goods_price FROM tdb_goods WHERE goods_price>ALL(SELECT goods_price FROM tdb_goods WHERE goodscate='超级本');+----------+----------------------------------+-------------+| goods_id | goods_name | goods_price |+----------+----------------------------------+-------------+| 3 | G150TH 15.6英寸游戏本 | 8499.000 || 13 | iMac ME086CH/A 21.5英寸一体电脑 | 9188.000 || 17 | Mac Pro MD878CH/A 专业级台式 脑 | 28888.000 |+----------+----------------------------------+-------------+3 rows in set (0.01 sec)mysql> #使用 in 和not in 引发的子查询；mysql> #EXIST 和not EXIST 引发的子查询mysql> #创建商品标签数据表：mysql> CREATE TABLE IF NOT EXISTS tdb_goods_cate( -> cate_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT, -> cate_name VARCHAR(40) NOT NULL -> );Query OK, 0 rows affected (0.18 sec)mysql> #得到商品分类；mysql> SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;+---------------+| goods_cate |+---------------+| 台式机 || 平板电脑 || 服务器/工作站 || 游戏本 || 笔记本 || 笔记本配件 || 超级本 |+---------------+7 rows in set (0.00 sec)mysql> #将查询的结果写入的数据表中、mysql> SELECT * FROM tdb_goods_cate;Empty set (0.00 sec)mysql> DESC tdb_goods_cate;+-----------+----------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-----------+----------------------+------+-----+---------+----------------+| cate_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || cate_name | varchar(40) | NO | | NULL | |+-----------+----------------------+------+-----+---------+----------------+2 rows in set (0.01 sec)mysql> INSERT tdb_goods_cate(cate_name) SELECT goods_cate FROM tdb_goods GROUP BY goods_cate;Query OK, 7 rows affected (0.04 sec)Records: 7 Duplicates: 0 Warnings: 0mysql> SELECT * FROM tdb_goods_cate;+---------+---------------+| cate_id | cate_name |+---------+---------------+| 1 | 台式机 || 2 | 平板电脑 || 3 | 服务器/工作站 || 4 | 游戏本 || 5 | 笔记本 || 6 | 笔记本配件 || 7 | 超级本 |+---------+---------------+7 rows in set (0.00 sec)mysql> #参照分类表更新商品表、mysql> UPDATE tdb_goods INNER JOIN tdb_goods_cate ON goods_cate=cate_name SET goods_cate=cate_id;Query OK, 22 rows affected (0.21 sec)Rows matched: 22 Changed: 22 Warnings: 0mysql> SELECT * FROM tdb_goods/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 goods_cate: 5 brand_name: 华硕goods_price: 3399.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 goods_cate: 5 brand_name: 联想goods_price: 4899.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 goods_cate: 4 brand_name: 雷神goods_price: 8499.000 is_show: 1 is_saleoff: 0*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 goods_cate: 5 brand_name: 华硕goods_price: 2799.000 is_show: 1 is_saleoff: 0*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 goods_cate: 7 brand_name: 联想goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 goods_cate: 7 brand_name: 联想goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 goods_cate: 7 brand_name: 索尼goods_price: 7999.000 is_show: 1 is_saleoff: 0*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 goods_cate: 2 brand_name: 苹果goods_price: 1998.000 is_show: 1 is_saleoff: 0*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） goods_cate: 2 brand_name: 苹果goods_price: 3388.000 is_show: 1 is_saleoff: 0*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） goods_cate: 2 brand_name: 苹果goods_price: 2788.000 is_show: 1 is_saleoff: 0*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 goods_cate: 1 brand_name: 联想goods_price: 3499.000 is_show: 1 is_saleoff: 0*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 goods_cate: 1 brand_name: 戴尔goods_price: 2899.000 is_show: 1 is_saleoff: 0*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 goods_cate: 1 brand_name: 苹果goods_price: 9188.000 is_show: 1 is_saleoff: 0*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） goods_cate: 1 brand_name: 宏碁goods_price: 3699.000 is_show: 1 is_saleoff: 0*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 goods_cate: 3 brand_name: 惠普goods_price: 4288.000 is_show: 1 is_saleoff: 0*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 goods_cate: 3 brand_name: 戴尔goods_price: 5388.000 is_show: 1 is_saleoff: 0*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 goods_cate: 3 brand_name: 苹果goods_price: 28888.000 is_show: 1 is_saleoff: 0*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 6 brand_name: 索尼goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 goods_cate: 6 brand_name: 索尼goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 goods_cate: 3 brand_name: IBMgoods_price: 6888.000 is_show: 1 is_saleoff: 0*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 6 brand_name: 索尼goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 goods_cate: 6 brand_name: 索尼goods_price: 99.000 is_show: 1 is_saleoff: 022 rows in set (0.00 sec)ERROR:No query specifiedmysql> SELECT * FROM tdb_goods_brands;+----------+------------+| brand_id | brand_name |+----------+------------+| 1 | IBM || 2 | 华硕 || 3 | 宏碁 || 4 | 惠普 || 5 | 戴尔 || 6 | 索尼 || 7 | 联想 || 8 | 苹果 || 9 | 雷神 |+----------+------------+9 rows in set (0.00 sec)mysql> SHOW COLUMNS FROM tdb_goods;+-------------+------------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-------------+------------------------+------+-----+---------+----------------+| goods_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || goods_name | varchar(150) | NO | | NULL | || goods_cate | varchar(40) | NO | | NULL | || brand_name | varchar(40) | NO | | NULL | || goods_price | decimal(15,3) unsigned | NO | | 0.000 | || is_show | tinyint(1) | NO | | 1 | || is_saleoff | tinyint(1) | NO | | 0 | |+-------------+------------------------+------+-----+---------+----------------+7 rows in set (0.03 sec)mysql> SHOW COLUMNS FROM tdb_goods_brands;+------------+----------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+------------+----------------------+------+-----+---------+----------------+| brand_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || brand_name | varchar(40) | NO | | NULL | |+------------+----------------------+------+-----+---------+----------------+2 rows in set (0.00 sec)mysql> 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;Query OK, 22 rows affected (0.06 sec)Rows matched: 22 Changed: 22 Warnings: 0mysql> SELECT * FROM tdb_goods/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 goods_cate: 5 brand_name: 2goods_price: 3399.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 goods_cate: 5 brand_name: 7goods_price: 4899.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 goods_cate: 4 brand_name: 9goods_price: 8499.000 is_show: 1 is_saleoff: 0*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 goods_cate: 5 brand_name: 2goods_price: 2799.000 is_show: 1 is_saleoff: 0*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 goods_cate: 7 brand_name: 7goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 goods_cate: 7 brand_name: 7goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 goods_cate: 7 brand_name: 6goods_price: 7999.000 is_show: 1 is_saleoff: 0*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 goods_cate: 2 brand_name: 8goods_price: 1998.000 is_show: 1 is_saleoff: 0*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） goods_cate: 2 brand_name: 8goods_price: 3388.000 is_show: 1 is_saleoff: 0*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） goods_cate: 2 brand_name: 8goods_price: 2788.000 is_show: 1 is_saleoff: 0*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 goods_cate: 1 brand_name: 7goods_price: 3499.000 is_show: 1 is_saleoff: 0*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 goods_cate: 1 brand_name: 5goods_price: 2899.000 is_show: 1 is_saleoff: 0*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 goods_cate: 1 brand_name: 8goods_price: 9188.000 is_show: 1 is_saleoff: 0*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） goods_cate: 1 brand_name: 3goods_price: 3699.000 is_show: 1 is_saleoff: 0*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 goods_cate: 3 brand_name: 4goods_price: 4288.000 is_show: 1 is_saleoff: 0*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 goods_cate: 3 brand_name: 5goods_price: 5388.000 is_show: 1 is_saleoff: 0*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 goods_cate: 3 brand_name: 8goods_price: 28888.000 is_show: 1 is_saleoff: 0*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 6 brand_name: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 goods_cate: 6 brand_name: 6goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 goods_cate: 3 brand_name: 1goods_price: 6888.000 is_show: 1 is_saleoff: 0*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 goods_cate: 6 brand_name: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 goods_cate: 6 brand_name: 6goods_price: 99.000 is_show: 1 is_saleoff: 022 rows in set (0.00 sec)ERROR:No query specifiedmysql> SHOW COLUMNS FROM tdb_goods;+-------------+------------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-------------+------------------------+------+-----+---------+----------------+| goods_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || goods_name | varchar(150) | NO | | NULL | || goods_cate | varchar(40) | NO | | NULL | || brand_name | varchar(40) | NO | | NULL | || goods_price | decimal(15,3) unsigned | NO | | 0.000 | || is_show | tinyint(1) | NO | | 1 | || is_saleoff | tinyint(1) | NO | | 0 | |+-------------+------------------------+------+-----+---------+----------------+7 rows in set (0.00 sec)mysql> ALTER TABLE tdb_goods -> CHANGE goods_cate cate_id SMALLINT UNSIGNED NOT NULL, -> CHANGE brand_name brand_id SMALLINT UNSIGNED NOT NULL;Query OK, 22 rows affected (0.67 sec)Records: 22 Duplicates: 0 Warnings: 0mysql> SHOW COLUMNS FROM tdb_goods;+-------------+------------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-------------+------------------------+------+-----+---------+----------------+| goods_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || goods_name | varchar(150) | NO | | NULL | || cate_id | smallint(5) unsigned | NO | | NULL | || brand_id | smallint(5) unsigned | NO | | NULL | || goods_price | decimal(15,3) unsigned | NO | | 0.000 | || is_show | tinyint(1) | NO | | 1 | || is_saleoff | tinyint(1) | NO | | 0 | |+-------------+------------------------+------+-----+---------+----------------+7 rows in set (0.00 sec)mysql> #创建一个事实的外键；mysql> SELECT * FROM tdb_goods/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 cate_id: 5 brand_id: 2goods_price: 3399.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 cate_id: 5 brand_id: 7goods_price: 4899.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 cate_id: 4 brand_id: 9goods_price: 8499.000 is_show: 1 is_saleoff: 0*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 cate_id: 5 brand_id: 2goods_price: 2799.000 is_show: 1 is_saleoff: 0*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 cate_id: 7 brand_id: 7goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 cate_id: 7 brand_id: 7goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 cate_id: 7 brand_id: 6goods_price: 7999.000 is_show: 1 is_saleoff: 0*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 cate_id: 2 brand_id: 8goods_price: 1998.000 is_show: 1 is_saleoff: 0*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） cate_id: 2 brand_id: 8goods_price: 3388.000 is_show: 1 is_saleoff: 0*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） cate_id: 2 brand_id: 8goods_price: 2788.000 is_show: 1 is_saleoff: 0*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 cate_id: 1 brand_id: 7goods_price: 3499.000 is_show: 1 is_saleoff: 0*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 cate_id: 1 brand_id: 5goods_price: 2899.000 is_show: 1 is_saleoff: 0*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 cate_id: 1 brand_id: 8goods_price: 9188.000 is_show: 1 is_saleoff: 0*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） cate_id: 1 brand_id: 3goods_price: 3699.000 is_show: 1 is_saleoff: 0*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 cate_id: 3 brand_id: 4goods_price: 4288.000 is_show: 1 is_saleoff: 0*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 cate_id: 3 brand_id: 5goods_price: 5388.000 is_show: 1 is_saleoff: 0*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 cate_id: 3 brand_id: 8goods_price: 28888.000 is_show: 1 is_saleoff: 0*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 cate_id: 6 brand_id: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 cate_id: 6 brand_id: 6goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 cate_id: 3 brand_id: 1goods_price: 6888.000 is_show: 1 is_saleoff: 0*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 cate_id: 6 brand_id: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 cate_id: 6 brand_id: 6goods_price: 99.000 is_show: 1 is_saleoff: 022 rows in set (0.00 sec)ERROR:No query specifiedmysql> INSERT tdb_goods_cates(cate_name) VALUES('路由器'),('交换机'),('网卡');ERROR 1146 (42S02): Table 'world.tdb_goods_cates' doesn't existmysql>mysql> INSERT tdb_goods_brands(brand_name) VALUES('海尔'),('清华同方'),('神舟');Query OK, 3 rows affected (0.07 sec)Records: 3 Duplicates: 0 Warnings: 0mysql> #在tdb_goods数据表写入任意记录mysql> 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');Query OK, 1 row affected (0.08 sec)mysql> SELECT * FROM tdb_goods_cate;+---------+---------------+| cate_id | cate_name |+---------+---------------+| 1 | 台式机 || 2 | 平板电脑 || 3 | 服务器/工作站 || 4 | 游戏本 || 5 | 笔记本 || 6 | 笔记本配件 || 7 | 超级本 |+---------+---------------+7 rows in set (0.03 sec)mysql> SELECT * FROM tdb_goods/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 cate_id: 5 brand_id: 2goods_price: 3399.000 is_show: 1 is_saleoff: 0*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 cate_id: 5 brand_id: 7goods_price: 4899.000 is_show: 1 is_saleoff: 0*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 cate_id: 4 brand_id: 9goods_price: 8499.000 is_show: 1 is_saleoff: 0*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 cate_id: 5 brand_id: 2goods_price: 2799.000 is_show: 1 is_saleoff: 0*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 cate_id: 7 brand_id: 7goods_price: 4999.000 is_show: 1 is_saleoff: 0*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 cate_id: 7 brand_id: 7goods_price: 4299.000 is_show: 1 is_saleoff: 0*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 cate_id: 7 brand_id: 6goods_price: 7999.000 is_show: 1 is_saleoff: 0*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 cate_id: 2 brand_id: 8goods_price: 1998.000 is_show: 1 is_saleoff: 0*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） cate_id: 2 brand_id: 8goods_price: 3388.000 is_show: 1 is_saleoff: 0*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） cate_id: 2 brand_id: 8goods_price: 2788.000 is_show: 1 is_saleoff: 0*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 cate_id: 1 brand_id: 7goods_price: 3499.000 is_show: 1 is_saleoff: 0*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 cate_id: 1 brand_id: 5goods_price: 2899.000 is_show: 1 is_saleoff: 0*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 cate_id: 1 brand_id: 8goods_price: 9188.000 is_show: 1 is_saleoff: 0*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） cate_id: 1 brand_id: 3goods_price: 3699.000 is_show: 1 is_saleoff: 0*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 cate_id: 3 brand_id: 4goods_price: 4288.000 is_show: 1 is_saleoff: 0*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 cate_id: 3 brand_id: 5goods_price: 5388.000 is_show: 1 is_saleoff: 0*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 cate_id: 3 brand_id: 8goods_price: 28888.000 is_show: 1 is_saleoff: 0*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 cate_id: 6 brand_id: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 cate_id: 6 brand_id: 6goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 cate_id: 3 brand_id: 1goods_price: 6888.000 is_show: 1 is_saleoff: 0*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 cate_id: 6 brand_id: 6goods_price: 6999.000 is_show: 1 is_saleoff: 0*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 cate_id: 6 brand_id: 6goods_price: 99.000 is_show: 1 is_saleoff: 0*************************** 23. row *************************** goods_id: 23 goods_name: LaserJet Pro P1606dn 黑白激光打印机 cate_id: 12 brand_id: 4goods_price: 1849.000 is_show: 1 is_saleoff: 023 rows in set (0.00 sec)ERROR:No query specifiedmysql> #数据表参照，用别名；mysql> #内链接 ，取交集；mysql> SHOW COLUMNS FROM tdb_goods;+-------------+------------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-------------+------------------------+------+-----+---------+----------------+| goods_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || goods_name | varchar(150) | NO | | NULL | || cate_id | smallint(5) unsigned | NO | | NULL | || brand_id | smallint(5) unsigned | NO | | NULL | || goods_price | decimal(15,3) unsigned | NO | | 0.000 | || is_show | tinyint(1) | NO | | 1 | || is_saleoff | tinyint(1) | NO | | 0 | |+-------------+------------------------+------+-----+---------+----------------+7 rows in set (0.00 sec)mysql> SHOW COLUMNS FROM tdb_goods_cate;+-----------+----------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-----------+----------------------+------+-----+---------+----------------+| cate_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || cate_name | varchar(40) | NO | | NULL | |+-----------+----------------------+------+-----+---------+----------------+2 rows in set (0.00 sec)mysql> SELECT goods_id,goods_name,cate_name -> FROM tdb_goods INNER JOIN tdb_goods_cate -> ON tdb_goods.cate_id=tdb_goods_cate.cate_id;+----------+------------------------------------------------------------------------+---------------+| goods_id | goods_name | cate_name |+----------+------------------------------------------------------------------------+---------------+| 1 | R510VC 15.6英寸笔记本 | 笔记本 || 2 | Y400N 14.0英寸笔记本电脑 | 笔记本 || 3 | G150TH 15.6英寸游戏本 | 游戏本 || 4 | X550CC 15.6英寸笔记本 | 笔记本 || 5 | X240(20ALA0EYCD) 12.5英寸超极本 | 超级本 || 6 | U330P 13.3英寸超极本 | 超级本 || 7 | SVP13226SCB 13.3英寸触控超极本 | 超级本 || 8 | iPad mini MD531CH/A 7.9英寸平板电脑 | 平板电脑 || 9 | iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） | 平板电脑 || 10 | 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 || 11 | IdeaCentre C340 20英寸一体电脑 | 台式机 || 12 | Vostro 3800-R1206 台式电脑 | 台式机 || 13 | iMac ME086CH/A 21.5英寸一体电脑 | 台式机 || 14 | AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） | 台式机 || 15 | Z220SFF F4F06PA工作站 | 服务器/工作站 || 16 | PowerEdge T110 II服务器 | 服务器/工作站 || 17 | Mac Pro MD878CH/A 专业级台式电脑 | 服务器/工作站 || 18 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 19 | 商务双肩背包 | 笔记本配件 || 20 | X3250 M4机架式服务器 2583i14 | 服务器/工作站 || 21 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 22 | 商务双肩背包 | 笔记本配件 |+----------+------------------------------------------------------------------------+---------------+22 rows in set (0.01 sec)mysql> SELECT * FROM tdb_goods_cate;+---------+---------------+| cate_id | cate_name |+---------+---------------+| 1 | 台式机 || 2 | 平板电脑 || 3 | 服务器/工作站 || 4 | 游戏本 || 5 | 笔记本 || 6 | 笔记本配件 || 7 | 超级本 |+---------+---------------+7 rows in set (0.00 sec)mysql> #左外连接，取左表中的全部和右表符合条件的部分；mysql> SELECT goods_id,goods_name,cate_name -> FROM tdb_goods LEFT JOIN tdb_goods_cate -> ON tdb_goods.cate_id=tdb_goods_cate.cate_id;+----------+------------------------------------------------------------------------+---------------+| goods_id | goods_name | cate_name |+----------+------------------------------------------------------------------------+---------------+| 1 | R510VC 15.6英寸笔记本 | 笔记本 || 2 | Y400N 14.0英寸笔记本电脑 | 笔记本 || 3 | G150TH 15.6英寸游戏本 | 游戏本 || 4 | X550CC 15.6英寸笔记本 | 笔记本 || 5 | X240(20ALA0EYCD) 12.5英寸超极本 | 超级本 || 6 | U330P 13.3英寸超极本 | 超级本 || 7 | SVP13226SCB 13.3英寸触控超极本 | 超级本 || 8 | iPad mini MD531CH/A 7.9英寸平板电脑 | 平板电脑 || 9 | iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） | 平板电脑 || 10 | 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 || 11 | IdeaCentre C340 20英寸一体电脑 | 台式机 || 12 | Vostro 3800-R1206 台式电脑 | 台式机 || 13 | iMac ME086CH/A 21.5英寸一体电脑 | 台式机 || 14 | AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） | 台式机 || 15 | Z220SFF F4F06PA工作站 | 服务器/工作站 || 16 | PowerEdge T110 II服务器 | 服务器/工作站 || 17 | Mac Pro MD878CH/A 专业级台式电脑 | 服务器/工作站 || 18 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 19 | 商务双肩背包 | 笔记本配件 || 20 | X3250 M4机架式服务器 2583i14 | 服务器/工作站 || 21 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 22 | 商务双肩背包 | 笔记本配件 || 23 | LaserJet Pro P1606dn 黑白激光打印机 | NULL |+----------+------------------------------------------------------------------------+---------------+23 rows in set (0.00 sec)mysql> #右外连接，取右表中的全部和左表符合条件的部分；mysql> SELECT goods_id,goods_name,cate_name -> FROM tdb_goods RIGHT JOIN tdb_goods_cate -> ON tdb_goods.cate_id=tdb_goods_cate.cate_id;+----------+------------------------------------------------------------------------+---------------+| goods_id | goods_name | cate_name |+----------+------------------------------------------------------------------------+---------------+| 1 | R510VC 15.6英寸笔记本 | 笔记本 || 2 | Y400N 14.0英寸笔记本电脑 | 笔记本 || 3 | G150TH 15.6英寸游戏本 | 游戏本 || 4 | X550CC 15.6英寸笔记本 | 笔记本 || 5 | X240(20ALA0EYCD) 12.5英寸超极本 | 超级本 || 6 | U330P 13.3英寸超极本 | 超级本 || 7 | SVP13226SCB 13.3英寸触控超极本 | 超级本 || 8 | iPad mini MD531CH/A 7.9英寸平板电脑 | 平板电脑 || 9 | iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） | 平板电脑 || 10 | 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 || 11 | IdeaCentre C340 20英寸一体电脑 | 台式机 || 12 | Vostro 3800-R1206 台式电脑 | 台式机 || 13 | iMac ME086CH/A 21.5英寸一体电脑 | 台式机 || 14 | AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） | 台式机 || 15 | Z220SFF F4F06PA工作站 | 服务器/工作站 || 16 | PowerEdge T110 II服务器 | 服务器/工作站 || 17 | Mac Pro MD878CH/A 专业级台式电脑 | 服务器/工作站 || 18 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 19 | 商务双肩背包 | 笔记本配件 || 20 | X3250 M4机架式服务器 2583i14 | 服务器/工作站 || 21 | HMZ-T3W 头戴显示设备 | 笔记本配件 || 22 | 商务双肩背包 | 笔记本配件 |+----------+------------------------------------------------------------------------+---------------+22 rows in set (0.02 sec)mysql> SELECT goods_id,goods_name,cate_name -> FROM tdb_goods LEFT JOIN tdb_goods_cate -> ON tdb_goods.cate_id=tdb_goods_cate.cate_id/G;*************************** 1. row *************************** goods_id: 1goods_name: R510VC 15.6英寸笔记本 cate_name: 笔记本*************************** 2. row *************************** goods_id: 2goods_name: Y400N 14.0英寸笔记本电脑 cate_name: 笔记本*************************** 3. row *************************** goods_id: 3goods_name: G150TH 15.6英寸游戏本 cate_name: 游戏本*************************** 4. row *************************** goods_id: 4goods_name: X550CC 15.6英寸笔记本 cate_name: 笔记本*************************** 5. row *************************** goods_id: 5goods_name: X240(20ALA0EYCD) 12.5英寸超极本 cate_name: 超级本*************************** 6. row *************************** goods_id: 6goods_name: U330P 13.3英寸超极本 cate_name: 超级本*************************** 7. row *************************** goods_id: 7goods_name: SVP13226SCB 13.3英寸触控超极本 cate_name: 超级本*************************** 8. row *************************** goods_id: 8goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 cate_name: 平板电脑*************************** 9. row *************************** goods_id: 9goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） cate_name: 平板电脑*************************** 10. row *************************** goods_id: 10goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） cate_name: 平板电脑*************************** 11. row *************************** goods_id: 11goods_name: IdeaCentre C340 20英寸一体电脑 cate_name: 台式机*************************** 12. row *************************** goods_id: 12goods_name: Vostro 3800-R1206 台式电脑 cate_name: 台式机*************************** 13. row *************************** goods_id: 13goods_name: iMac ME086CH/A 21.5英寸一体电脑 cate_name: 台式机*************************** 14. row *************************** goods_id: 14goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） cate_name: 台式机*************************** 15. row *************************** goods_id: 15goods_name: Z220SFF F4F06PA工作站 cate_name: 服务器/工作站*************************** 16. row *************************** goods_id: 16goods_name: PowerEdge T110 II服务器 cate_name: 服务器/工作站*************************** 17. row *************************** goods_id: 17goods_name: Mac Pro MD878CH/A 专业级台式电脑 cate_name: 服务器/工作站*************************** 18. row *************************** goods_id: 18goods_name: HMZ-T3W 头戴显示设备 cate_name: 笔记本配件*************************** 19. row *************************** goods_id: 19goods_name: 商务双肩背包 cate_name: 笔记本配件*************************** 20. row *************************** goods_id: 20goods_name: X3250 M4机架式服务器 2583i14 cate_name: 服务器/工作站*************************** 21. row *************************** goods_id: 21goods_name: HMZ-T3W 头戴显示设备 cate_name: 笔记本配件*************************** 22. row *************************** goods_id: 22goods_name: 商务双肩背包 cate_name: 笔记本配件*************************** 23. row *************************** goods_id: 23goods_name: LaserJet Pro P1606dn 黑白激光打印机 cate_name: NULL23 rows in set (0.00 sec)ERROR:No query specifiedmysql> #多表连接；mysql> SHOW COLUMNS FROM tdb_goods/G;*************************** 1. row *************************** Field: goods_id Type: smallint(5) unsigned Null: NO Key: PRIDefault: NULL Extra: auto_increment*************************** 2. row *************************** Field: goods_name Type: varchar(150) Null: NO Key:Default: NULL Extra:*************************** 3. row *************************** Field: cate_id Type: smallint(5) unsigned Null: NO Key:Default: NULL Extra:*************************** 4. row *************************** Field: brand_id Type: smallint(5) unsigned Null: NO Key:Default: NULL Extra:*************************** 5. row *************************** Field: goods_price Type: decimal(15,3) unsigned Null: NO Key:Default: 0.000 Extra:*************************** 6. row *************************** Field: is_show Type: tinyint(1) Null: NO Key:Default: 1 Extra:*************************** 7. row *************************** Field: is_saleoff Type: tinyint(1) Null: NO Key:Default: 0 Extra:7 rows in set (0.00 sec)ERROR:No query specifiedmysql> #实现三张表的连接；mysql> SELECT goods_id,goods_name,cate_name,brand_name,goods_price FROM tdb_goods AS g -> INNER JOIN tdb_goods_cate AS c -> ON g.cate_id=c.cate_id -> INNER JOIN tdb_goods_brands AS b -> ON g.brand_id=b.brand_id/G;*************************** 1. row *************************** goods_id: 1 goods_name: R510VC 15.6英寸笔记本 cate_name: 笔记本 brand_name: 华硕goods_price: 3399.000*************************** 2. row *************************** goods_id: 2 goods_name: Y400N 14.0英寸笔记本电脑 cate_name: 笔记本 brand_name: 联想goods_price: 4899.000*************************** 3. row *************************** goods_id: 3 goods_name: G150TH 15.6英寸游戏本 cate_name: 游戏本 brand_name: 雷神goods_price: 8499.000*************************** 4. row *************************** goods_id: 4 goods_name: X550CC 15.6英寸笔记本 cate_name: 笔记本 brand_name: 华硕goods_price: 2799.000*************************** 5. row *************************** goods_id: 5 goods_name: X240(20ALA0EYCD) 12.5英寸超极本 cate_name: 超级本 brand_name: 联想goods_price: 4999.000*************************** 6. row *************************** goods_id: 6 goods_name: U330P 13.3英寸超极本 cate_name: 超级本 brand_name: 联想goods_price: 4299.000*************************** 7. row *************************** goods_id: 7 goods_name: SVP13226SCB 13.3英寸触控超极本 cate_name: 超级本 brand_name: 索尼goods_price: 7999.000*************************** 8. row *************************** goods_id: 8 goods_name: iPad mini MD531CH/A 7.9英寸平板电脑 cate_name: 平板电脑 brand_name: 苹果goods_price: 1998.000*************************** 9. row *************************** goods_id: 9 goods_name: iPad Air MD788CH/A 9.7英寸平板电脑 （16G WiFi版） cate_name: 平板电脑 brand_name: 苹果goods_price: 3388.000*************************** 10. row *************************** goods_id: 10 goods_name: iPad mini ME279CH/A 配备 Retina 显示屏 7.9英寸平板电脑 （16G WiFi版） cate_name: 平板电脑 brand_name: 苹果goods_price: 2788.000*************************** 11. row *************************** goods_id: 11 goods_name: IdeaCentre C340 20英寸一体电脑 cate_name: 台式机 brand_name: 联想goods_price: 3499.000*************************** 12. row *************************** goods_id: 12 goods_name: Vostro 3800-R1206 台式电脑 cate_name: 台式机 brand_name: 戴尔goods_price: 2899.000*************************** 13. row *************************** goods_id: 13 goods_name: iMac ME086CH/A 21.5英寸一体电脑 cate_name: 台式机 brand_name: 苹果goods_price: 9188.000*************************** 14. row *************************** goods_id: 14 goods_name: AT7-7414LP 台式电脑 （i5-3450四核 4G 500G 2G独显 DVD 键鼠 Linux ） cate_name: 台式机 brand_name: 宏碁goods_price: 3699.000*************************** 15. row *************************** goods_id: 15 goods_name: Z220SFF F4F06PA工作站 cate_name: 服务器/工作站 brand_name: 惠普goods_price: 4288.000*************************** 16. row *************************** goods_id: 16 goods_name: PowerEdge T110 II服务器 cate_name: 服务器/工作站 brand_name: 戴尔goods_price: 5388.000*************************** 17. row *************************** goods_id: 17 goods_name: Mac Pro MD878CH/A 专业级台式电脑 cate_name: 服务器/工作站 brand_name: 苹果goods_price: 28888.000*************************** 18. row *************************** goods_id: 18 goods_name: HMZ-T3W 头戴显示设备 cate_name: 笔记本配件 brand_name: 索尼goods_price: 6999.000*************************** 19. row *************************** goods_id: 19 goods_name: 商务双肩背包 cate_name: 笔记本配件 brand_name: 索尼goods_price: 99.000*************************** 20. row *************************** goods_id: 20 goods_name: X3250 M4机架式服务器 2583i14 cate_name: 服务器/工作站 brand_name: IBMgoods_price: 6888.000*************************** 21. row *************************** goods_id: 21 goods_name: HMZ-T3W 头戴显示设备 cate_name: 笔记本配件 brand_name: 索尼goods_price: 6999.000*************************** 22. row *************************** goods_id: 22 goods_name: 商务双肩背包 cate_name: 笔记本配件 brand_name: 索尼goods_price: 99.00022 rows in set (0.02 sec)ERROR:No query specifiedmysql>mysql> #SHOW COLUMNS FROM tdb_goods_cate;mysql> SHOW COLUMNS FROM tdb_goods_cate;+-----------+----------------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+-----------+----------------------+------+-----+---------+----------------+| cate_id | smallint(5) unsigned | NO | PRI | NULL | auto_increment || cate_name | varchar(40) | NO | | NULL | |+-----------+----------------------+------+-----+---------+----------------+2 rows in set (0.00 sec)mysql> SELECT * FROM tdb_goods_cate;+---------+---------------+| cate_id | cate_name |+---------+---------------+| 1 | 台式机 || 2 | 平板电脑 || 3 | 服务器/工作站 || 4 | 游戏本 || 5 | 笔记本 || 6 | 笔记本配件 || 7 | 超级本 |+---------+---------------+7 rows in set (0.00 sec)mysql> 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 -> );Query OK, 0 rows affected (0.19 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('家用电器',DEFAULT);Query OK, 1 row affected (0.05 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('电脑、办公',DEFAULT);Query OK, 1 row affected (0.02 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('大家电',1);Query OK, 1 row affected (0.06 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('生活电器',1);Query OK, 1 row affected (0.05 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('平板电视',3);Query OK, 1 row affected (0.02 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('空调',3);Query OK, 1 row affected (0.02 sec)mysql> INSERT tdb_goods_types(type_name,parent_id) VALUES('电风扇',4);Query OK, 1 row affected (0.02 sec)mysql> INSERT tdb_goods_types(ty以上就是MySQL基础五：子查询与链接_MySQL的内容， |