在 MySQL 数据库中,我有下表
CREATE TABLE `store` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`storetypeID` int(10) unsigned NOT NULL,
`storename` varchar(100) NOT NULL,
`VATnumber` char(9) NOT NULL,
`visits` int(10) unsigned DEFAULT '0000000000',
PRIMARY KEY (`ID`),
UNIQUE KEY `ID_UNIQUE` (`ID`),
UNIQUE KEY `VATnumber_UNIQUE` (`VATnumber`),
KEY `storeID_idx` (`storetypeID`),
CONSTRAINT `storeID` FOREIGN KEY (`storetypeID`) REFERENCES `storetype` (`ID`) ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=947 DEFAULT CHARSET=utf8;
CREATE TABLE `expenses` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`storeID` int(10) unsigned DEFAULT NULL,
`expensedate` date NOT NULL,
`amount` decimal(10,2) NOT NULL,
PRIMARY KEY (`ID`),
UNIQUE KEY `ID_UNIQUE` (`ID`),
KEY `storeID_idx` (`storeID`),
CONSTRAINT `storeIDidx` FOREIGN KEY (`storeID`) REFERENCES `store` (`ID`) ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=7502 DEFAULT CHARSET=utf8;
使用以下查询,我可以获得每个商店的费用数量。
SELECT COUNT(*) AS visits, storeID FROM taxfriend.expenses GROUP BY storeID ORDER BY visits desc
有了这个结果,我想用查询中的字段访问来更新表存储中的字段访问。 一种选择是编写一个小子例程(例如使用 VB)。
有什么方法可以在 MySQL 中创建 UPDATE 查询来完成此操作吗?
最佳答案
您可以在 UPDATE
查询中使用 JOIN
。
UPDATE store AS s
JOIN (SELECT COUNT(*) AS visits, storeID
FROM taxfriend.expenses
GROUP BY storeID) AS e
ON s.ID = e.storeID
SET s.visits = e.visits
关于mysql - 使用查询结果更新表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43598080/