子查询

CREATE TABLE `userinfo` (
`id` int(11) NOT NULL,
`name` varchar(32) DEFAULT NULL,
`depid` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- ----------------------------
-- Records of userinfo
-- ----------------------------
INSERT INTO `userinfo` VALUES ('2', 'lip2', '2');
INSERT INTO `userinfo` VALUES ('1', 'lip', '1');

CREATE TABLE `department` (
`id` int(11) DEFAULT NULL,
`name` varchar(32) DEFAULT NULL,
`isDel` smallint(6) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- ----------------------------
-- Records of department
-- ----------------------------
INSERT INTO `department` VALUES ('1', 'test', '1');
INSERT INTO `department` VALUES ('1', 'test', '0');
INSERT INTO `department` VALUES ('2', 'haha', '0');
INSERT INTO `department` VALUES ('2', 'xixi', '0');

select * from userinfo;
select * from department

SELECT id,name,(select `name` from department where id=depid limit 1)as depname from userinfo    ------mysql

SELECT id,name,age,(SELECT TOP 1 name FROM dbo.Department WHERE id=depid )AS depname FROM dbo.UserInfo   ------sql server

子查询