MyBatis图文并茂讲解注解开发一对一查询

第MyBatis图文并茂讲解注解开发一对一查询目录MyBatis的注解实现复杂映射开发一对一查询一对一查询的模型一对一查询的语句创建PersonMapper接口使用注解配置Mapper测试类一对一配置总结

MyBatis的注解实现复杂映射开发

实现复杂关系映射之前我们可以在映射文件中通过配置来实现，使用注解开发后，我们可以使用@Results注解，@Result注解，@One注解，@Many注解组合完成复杂关系的配置

一对一查询

一对一查询的模型

一对一查询的需求：查询一个用户信息，与此同时查询出该用户对应的身份证信息

一对一查询的语句

创建数据库：

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--Tablestructureforcard

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DROPTABLEIFEXISTS`card`;

CREATETABLE`card`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`number`varchar(30)CHARACTERSETutf8mb4COLLATEutf8mb4_unicode_ciNULLDEFAULTNULL,

`pid`int(11)NULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE,

INDEX`cp_fk`(`pid`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=4CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Dynamic;

------------------------------

--Recordsofcard

------------------------------

INSERTINTO`card`VALUES(1,'12345',1);

INSERTINTO`card`VALUES(2,'23456',2);

INSERTINTO`card`VALUES(3,'34567',3);

------------------------------

--Tablestructureforclasses

------------------------------

DROPTABLEIFEXISTS`classes`;

CREATETABLE`classes`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`NAME`varchar(20)CHARACTERSETutf8mb4COLLATEutf8mb4_unicode_ciNULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=3CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Dynamic;

------------------------------

--Recordsofclasses

------------------------------

INSERTINTO`classes`VALUES(1,'极地一班');

INSERTINTO`classes`VALUES(2,'极地二班');

------------------------------

--Tablestructureforcourse

------------------------------

DROPTABLEIFEXISTS`course`;

CREATETABLE`course`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`NAME`varchar(20)CHARACTERSETutf8mb4COLLATEutf8mb4_unicode_ciNULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=3CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Dynamic;

------------------------------

--Recordsofcourse

------------------------------

INSERTINTO`course`VALUES(1,'语文');

INSERTINTO`course`VALUES(2,'数学');

------------------------------

--Tablestructureforperson

------------------------------

DROPTABLEIFEXISTS`person`;

CREATETABLE`person`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`NAME`varchar(20)CHARACTERSETutf8mb4COLLATEutf8mb4_unicode_ciNULLDEFAULTNULL,

`age`int(11)NULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=4CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Dynamic;

------------------------------

--Recordsofperson

------------------------------

INSERTINTO`person`VALUES(1,'张三',23);

INSERTINTO`person`VALUES(2,'李四',24);

INSERTINTO`person`VALUES(3,'王五',25);

------------------------------

--Tablestructureforstu_cr

------------------------------

DROPTABLEIFEXISTS`stu_cr`;

CREATETABLE`stu_cr`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`sid`int(11)NULLDEFAULTNULL,

`cid`int(11)NULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE,

INDEX`sc_fk1`(`sid`)USINGBTREE,

INDEX`sc_fk2`(`cid`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=5CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Fixed;

------------------------------

--Recordsofstu_cr

------------------------------

INSERTINTO`stu_cr`VALUES(1,1,1);

INSERTINTO`stu_cr`VALUES(2,1,2);

INSERTINTO`stu_cr`VALUES(3,2,1);

INSERTINTO`stu_cr`VALUES(4,2,2);

------------------------------

--Tablestructureforstudent

------------------------------

DROPTABLEIFEXISTS`student`;

CREATETABLE`student`(

`id`int(11)NOTNULLAUTO_INCREMENT,

`NAME`varchar(30)CHARACTERSETutf8mb4COLLATEutf8mb4_unicode_ciNULLDEFAULTNULL,

`age`int(11)NULLDEFAULTNULL,

`cid`int(11)NULLDEFAULTNULL,

PRIMARYKEY(`id`)USINGBTREE,

INDEX`cs_fk`(`cid`)USINGBTREE

)ENGINE=MyISAMAUTO_INCREMENT=5CHARACTERSET=utf8mb4COLLATE=utf8mb4_unicode_ciROW_FORMAT=Dynamic;

------------------------------

--Recordsofstudent

------------------------------

INSERTINTO`student`VALUES(1,'张三',23,1);

INSERTINTO`student`VALUES(2,'李四',24,1);

INSERTINTO`student`VALUES(3,'王五',25,2);

INSERTINTO`student`VALUES(4,'赵六',26,2);

SETFOREIGN_KEY_CHECKS=1;

对应的sql语句：

SELECT*FROMcard；

SELECT*FROMpersonWHEREid=#{id};

创建PersonMapper接口

publicinterfacePersonMapper{

//根据id查询

@Select("SELECT*FROMpersonWHEREid=#{id}")

publicabstractPersonselectById(Integerid);

}

使用注解配置Mapper

publicinterfaceCardMapper{

//查询全部

@Select("SELECT*FROMcard")

@Results({

@Result(column="id",property="id"),

@Result(column="number",property="number"),

@Result(

property="p",//被包含对象的变量名

javaType=Person.class,//被包含对象的实际数据类型

column="pid",//根据查询出的card表中的pid字段来查询person表

one、@One一对一固定写法

select属性：指定调用哪个接口中的哪个方法

one=@One(select="com.yyl.one_to_one.PersonMapper.selectById")

publicabstractListCardselectAll();

}

测试类

publicclassTest01{

@Test

publicvoidselectAll()throwsException{

//1.加载核心配置文件

InputStreamis=Resources.getResourceAsStream("MyBatisConfig.xml");

//2.获取SqlSession工厂对象

SqlSessionFactorysqlSessionFactory=newSqlSessionFactoryBuilder().build(is);