首先先来说明一下数据库,数据库有两张表student表和teacher表:

student表如下:

mybatis学习——多对一和一对多查询

teacher表如下:

mybatis学习——多对一和一对多查询

 

两张表的关系:多个学生关联一位老师(多对一)

*其中tid是外键

mybatis学习——多对一和一对多查询

需要sql语句的朋友可以在这里取:

CREATE TABLE `teacher`(
    `id` INT(10) NOT NULL,
    `name` VARCHAR(30) DEFAULT NULL,
    PRIMARY KEY(`id`)
)ENGINE=INNODB DEFAULT CHARSET=utf8

INSERT INTO teacher(`id`,`name`) VALUES (1,'秦老师');

CREATE TABLE `student`(
    `id` INT(10) NOT NULL,
    `name` VARCHAR(30) DEFAULT NULL,
    `tid` INT(10) DEFAULT NULL,
    PRIMARY KEY(`id`),
    KEY `fktid` (`tid`),
    CONSTRAINT `fktid` FOREIGN KEY (`tid`) REFERENCES `teacher` (`id`)
)ENGINE=INNODB DEFAULT CHARSET=utf8

INSERT INTO `student`(`id`,`name`,`tid`) VALUES ('1','小明','1');
INSERT INTO `student`(`id`,`name`,`tid`) VALUES ('2','小红','1');
INSERT INTO `student`(`id`,`name`,`tid`) VALUES ('3','小张','1');
INSERT INTO `student`(`id`,`name`,`tid`) VALUES ('4','小李','1');
INSERT INTO `student`(`id`,`name`,`tid`) VALUES ('5','小王','1');

SELECT * FROM student;
SELECT * FROM teacher;
View Code

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