MySQL：将逗号分隔值与不同行中的值进行比较

Question

我有以下要求。

我有两个表T1和T2，如

表T1

Product     Geography
P1          G1
P2          G1
P2          G2

表T2

Product     Geography
P1          G1, G2
P2          G1, G2

如果逗号分隔的Geography在T1中具有完全匹配的记录，我想要查询从表T2获取数据。如果任何表中的地理位置越来越少，则不应返回该行。 T2中的地理顺序不固定。因此，从上面的示例返回该查询将是：

Product     Geography
P2          G1, G2

Answer 1

加入联合值

SELECT t2.Product,t2.geography FROM t2
JOIN 
(SELECT  t1.Product,GROUP_CONCAT(t1.geography ORDER BY t1.Geography SEPARATOR ', ') as concatgeo FROM t1
GROUP BY t1.product)x
ON t2.Geography=x.concatgeo AND t2.Product=x.Product

Answer 2

SELECT 
firstTable.Product,
firstTable.geographies
FROM
(
   SELECT 
    Product,
    REPLACE(GROUP_CONCAT(Geography),' ','') AS geographies
   FROM T1
   GROUP BY Product) firstTable

INNER JOIN 

(
   SELECT 
    Product,
    REPLACE(Geography,' ','') AS geographies
   FROM T2 ) secondTable

ON firstTable.Product = secondTable.Product
WHERE firstTable.geographies = secondTable.geographies;

注意：我已使用REPLACE函数替换空格，以确保两个表中的两个查询生成相同的字符串

SQL FIDDLE DEMO

TEST（如果您无法访问sqlfiddle）：

DROP TABLE IF EXISTS `t1`;
CREATE TABLE `t1` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `Product` varchar(50) CHARACTER SET utf8 NOT NULL,
  `Geography` varchar(100) CHARACTER SET utf8 NOT NULL,
  PRIMARY KEY (`ID`)
);
INSERT INTO `t1` VALUES ('1', 'P1', 'G1');
INSERT INTO `t1` VALUES ('2', 'P2', 'G1');
INSERT INTO `t1` VALUES ('3', 'P2', 'G2');

DROP TABLE IF EXISTS `t2`;
CREATE TABLE `t2` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `Product` varchar(50) CHARACTER SET utf8 NOT NULL,
  `Geography` varchar(100) CHARACTER SET utf8 NOT NULL,
  PRIMARY KEY (`ID`)
);
INSERT INTO `t2` VALUES ('1', 'P1', 'G1, G2');
INSERT INTO `t2` VALUES ('2', 'P2', 'G1, G2');

对此测试数据运行上述查询，您将获得如下输出：

Product geographies
P2         G1,G2