CREATE TABLE `User`
(
`Id` BIGINT AUTO_INCREMENT NOT NULL,
`Name` VARCHAR(10) NULL,
`Phone` VARCHAR(100) NULL,
`IsDeleted` TINYINT NULL,
PRIMARY KEY (Id)
);
CREATE TABLE `Email`
(
`Id` BIGINT AUTO_INCREMENT NOT NULL,
`FjUserId` BIGINT NULL,
`SjUserId` BIGINT NULL,
`CsUserId` BIGINT NULL,
`IsDeleted` TINYINT NULL,
PRIMARY KEY (Id)
);
方案一：
SELECT e.*
,u1.`Name`
,u2.`Name`
,u3.`Name`
FROM(SELECT * FROM `EmailTest` WHERE `IsDeleted` = 0) e
LEFT JOIN (SELECT * FROM `UserTest` WHERE `IsDeleted` = 0) u1
ON u1.`Id` = e.`FjUserId`
LEFT JOIN (SELECT * FROM `UserTest` WHERE `IsDeleted` = 0) u2
ON u2.`Id` = e.`SjUserId`
LEFT JOIN (SELECT * FROM `UserTest` WHERE `IsDeleted` = 0) u3
ON u3.`Id` = e.`CsUserId`;
方案二：
SELECT e.*
,( SELECT `Name` FROM `UserTest` WHERE e.`FjUserId` = `Id` AND `IsDeleted` = 0) AS `Name1`
,( SELECT `Name` FROM `UserTest` WHERE e.`SjUserId` = `Id` AND `IsDeleted` = 0) AS `Name2`
,( SELECT `Name` FROM `UserTest` WHERE e.`CsUserId` = `Id` AND `IsDeleted` = 0) AS `Name3`
FROM `EmailTest` e
WHERE `IsDeleted` = 0;