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07-查询操作(DQL)-多表查询
一. 综述
查询操作主要从两个方面来说：单表查询和多表查询。 多表查询包括：笛卡尔积、外键约束、内连接查询、外链接查询、自连接查询。
二 . 案例设计
1. 设计产品表（product）。包括：主键id、产品名称（productName）、分类编号（dir_id）、零售价（salePrice）、供应商（supplier）、品牌（brand）、折扣（cutoff）、成本价（costPrice）。
设计产品产品编号表( productdir)。 包括：主键id、编号名称( dirName)、父id( parent_id) 。
设计产品库存表( productstock)。包括：主键id、产品id( product_id )、库存数量( storeNum)、上次进库时间（lastIncomeDate）、上次出库时间( lastOutcomeDate)、预警数量（warningNum）。
对应的SQL语句：
1 CREATE TABLE `product` (
2 `id` bigint(11) NOT NULL AUTO_INCREMENT,
3 `productName` varchar(50) DEFAULT NULL,
4 `dir_id` bigint(11) DEFAULT NULL,
5 `salePrice` double(10,2) DEFAULT NULL,
6 `supplier` varchar(50) DEFAULT NULL,
7 `brand` varchar(50) DEFAULT NULL,
8 `cutoff` double(2,2) DEFAULT NULL,
9 `costPrice` double(10,2) DEFAULT NULL,
10 PRIMARY KEY (`id`)
11 ) ENGINE=MyISAM AUTO_INCREMENT=21 DEFAULT CHARSET=utf8;
12
13 -- ----------------------------
14 -- Records of product
15 -- ----------------------------
16 INSERT INTO `product` VALUES (‘1‘, ‘罗技M90‘, ‘3‘, ‘90.00‘, ‘罗技‘, ‘罗技‘, ‘0.50‘, ‘35.00‘);
17 INSERT INTO `product` VALUES (‘2‘, ‘罗技M100‘, ‘3‘, ‘49.00‘, ‘罗技‘, ‘罗技‘, ‘0.90‘, ‘33.00‘);
18 INSERT INTO `product` VALUES (‘3‘, ‘罗技M115‘, ‘3‘, ‘99.00‘, ‘罗技‘, ‘罗技‘, ‘0.60‘, ‘38.00‘);
19 INSERT INTO `product` VALUES (‘4‘, ‘罗技M125‘, ‘3‘, ‘80.00‘, ‘罗技‘, ‘罗技‘, ‘0.90‘, ‘39.00‘);
20 INSERT INTO `product` VALUES (‘5‘, ‘罗技木星轨迹球‘, ‘3‘, ‘182.00‘, ‘罗技‘, ‘罗技‘, ‘0.80‘, ‘80.00‘);
21 INSERT INTO `product` VALUES (‘6‘, ‘罗技火星轨迹球‘, ‘3‘, ‘349.00‘, ‘罗技‘, ‘罗技‘, ‘0.87‘, ‘290.00‘);
22 INSERT INTO `product` VALUES (‘7‘, ‘罗技G9X‘, ‘3‘, ‘680.00‘, ‘罗技‘, ‘罗技‘, ‘0.70‘, ‘470.00‘);
23 INSERT INTO `product` VALUES (‘8‘, ‘罗技M215‘, ‘2‘, ‘89.00‘, ‘罗技‘, ‘罗技‘, ‘0.79‘, ‘30.00‘);
24 INSERT INTO `product` VALUES (‘9‘, ‘罗技M305‘, ‘2‘, ‘119.00‘, ‘罗技‘, ‘罗技‘, ‘0.82‘, ‘48.00‘);
25 INSERT INTO `product` VALUES (‘10‘, ‘罗技M310‘, ‘2‘, ‘135.00‘, ‘罗技‘, ‘罗技‘, ‘0.92‘, ‘69.80‘);
26 INSERT INTO `product` VALUES (‘11‘, ‘罗技M505‘, ‘2‘, ‘148.00‘, ‘罗技‘, ‘罗技‘, ‘0.92‘, ‘72.00‘);
27 INSERT INTO `product` VALUES (‘12‘, ‘罗技M555‘, ‘2‘, ‘275.00‘, ‘罗技‘, ‘罗技‘, ‘0.88‘, ‘140.00‘);
28 INSERT INTO `product` VALUES (‘13‘, ‘罗技M905‘, ‘2‘, ‘458.00‘, ‘罗技‘, ‘罗技‘, ‘0.88‘, ‘270.00‘);
29 INSERT INTO `product` VALUES (‘14‘, ‘罗技MX1100‘, ‘2‘, ‘551.00‘, ‘罗技‘, ‘罗技‘, ‘0.76‘, ‘300.00‘);
30 INSERT INTO `product` VALUES (‘15‘, ‘罗技M950‘, ‘2‘, ‘678.00‘, ‘罗技‘, ‘罗技‘, ‘0.78‘, ‘320.00‘);
31 INSERT INTO `product` VALUES (‘16‘, ‘罗技MX Air‘, ‘2‘, ‘1299.00‘, ‘罗技‘, ‘罗技‘, ‘0.72‘, ‘400.00‘);
32 INSERT INTO `product` VALUES (‘17‘, ‘罗技G1‘, ‘4‘, ‘155.00‘, ‘罗技‘, ‘罗技‘, ‘0.80‘, ‘49.00‘);
33 INSERT INTO `product` VALUES (‘18‘, ‘罗技G3‘, ‘4‘, ‘229.00‘, ‘罗技‘, ‘罗技‘, ‘0.77‘, ‘96.00‘);
34 INSERT INTO `product` VALUES (‘19‘, ‘罗技G500‘, ‘4‘, ‘399.00‘, ‘罗技‘, ‘罗技‘, ‘0.88‘, ‘130.00‘);
35 INSERT INTO `product` VALUES (‘20‘, ‘罗技G700‘, ‘4‘, ‘699.00‘, ‘罗技‘, ‘罗技‘, ‘0.79‘, ‘278.00‘);
CREATE TABLE `productdir` (
`id` bigint(11) NOT NULL auto_increment,
`dirName` varchar(30) default NULL,
`parent_id` bigint(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records
-- ----------------------------
INSERT INTO `productdir` VALUES (‘1‘, ‘鼠标‘, null);
INSERT INTO `productdir` VALUES (‘2‘, ‘无线鼠标‘, ‘1‘);
INSERT INTO `productdir` VALUES (‘3‘, ‘有线鼠标‘, ‘1‘);
INSERT INTO `productdir` VALUES (‘4‘, ‘游戏鼠标‘, ‘1‘);
CREATE TABLE `productstock` (
`id` bigint(11) NOT NULL auto_increment,
`product_id` bigint(11) default NULL,
`storeNum` int(10) default NULL,
`lastIncomeDate` datetime default NULL,
`lastOutcomeDate` datetime default NULL,
`warningNum` int(10) default NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records
-- ----------------------------
INSERT INTO `productstock` VALUES (‘1‘, ‘1‘, ‘182‘, ‘2015-03-12 20:33:00‘, ‘2015-03-12 20:33:04‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘2‘, ‘2‘, ‘27‘, ‘2015-03-02 20:33:28‘, ‘2015-03-09 20:33:40‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘3‘, ‘3‘, ‘89‘, ‘2015-02-28 20:34:13‘, ‘2015-03-12 20:34:19‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘4‘, ‘5‘, ‘19‘, ‘2015-03-01 20:34:43‘, ‘2015-03-12 20:34:48‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘5‘, ‘6‘, ‘3‘, ‘2015-02-01 20:35:12‘, ‘2015-03-02 20:35:16‘, ‘5‘);
INSERT INTO `productstock` VALUES (‘6‘, ‘7‘, ‘2‘, ‘2015-02-02 20:35:59‘, ‘2015-02-27 20:36:05‘, ‘3‘);
INSERT INTO `productstock` VALUES (‘7‘, ‘8‘, ‘120‘, ‘2015-03-12 20:36:31‘, ‘2015-03-12 20:36:33‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘8‘, ‘9‘, ‘58‘, ‘2015-03-02 20:36:50‘, ‘2015-03-12 20:36:53‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘9‘, ‘11‘, ‘28‘, ‘2015-03-02 20:37:12‘, ‘2015-03-12 20:37:15‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘10‘, ‘12‘, ‘8‘, ‘2015-03-02 20:37:35‘, ‘2015-03-09 20:37:38‘, ‘5‘);
INSERT INTO `productstock` VALUES (‘11‘, ‘13‘, ‘3‘, ‘2015-03-02 20:37:58‘, ‘2015-03-12 20:38:01‘, ‘5‘);
INSERT INTO `productstock` VALUES (‘12‘, ‘14‘, ‘6‘, ‘2015-03-02 20:38:20‘, ‘2015-03-07 20:38:23‘, ‘5‘);
INSERT INTO `productstock` VALUES (‘13‘, ‘15‘, ‘2‘, ‘2015-02-02 20:38:38‘, ‘2015-02-24 20:38:44‘, ‘5‘);
INSERT INTO `productstock` VALUES (‘14‘, ‘16‘, ‘3‘, ‘2015-02-02 20:39:05‘, ‘2015-02-06 20:39:09‘, ‘3‘);
INSERT INTO `productstock` VALUES (‘15‘, ‘17‘, ‘49‘, ‘2015-03-02 20:39:36‘, ‘2015-03-12 20:39:40‘, ‘20‘);
INSERT INTO `productstock` VALUES (‘16‘, ‘18‘, ‘14‘, ‘2015-03-02 20:39:57‘, ‘2015-03-09 20:40:01‘, ‘10‘);
INSERT INTO `productstock` VALUES (‘17‘, ‘20‘, ‘7‘, ‘2015-03-02 20:40:22‘, ‘2015-03-03 20:40:25‘, ‘5‘);
07-查询操作(DQL)-多表查询
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