MyBatis圖文并茂講解注解開發(fā)一對一查詢

第MyBatis圖文并茂講解注解開發(fā)一對一查詢目錄MyBatis的注解實現(xiàn)復(fù)雜映射開發(fā)一對一查詢一對一查詢的模型一對一查詢的語句創(chuàng)建PersonMapper接口使用注解配置Mapper測試類一對一配置總結(jié)

MyBatis的注解實現(xiàn)復(fù)雜映射開發(fā)

實現(xiàn)復(fù)雜關(guān)系映射之前我們可以在映射文件中通過配置來實現(xiàn)，使用注解開發(fā)后，我們可以使用@Results注解，@Result注解，@One注解，@Many注解組合完成復(fù)雜關(guān)系的配置

一對一查詢

一對一查詢的模型

一對一查詢的需求：查詢一個用戶信息，與此同時查詢出該用戶對應(yīng)的身份證信息

一對一查詢的語句

創(chuàng)建數(shù)據(jù)庫：

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--Tablestructureforcard

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

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,'極地一班');

INSERTINTO`classes`VALUES(2,'極地二班');

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

--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,'語文');

INSERTINTO`course`VALUES(2,'數(shù)學');

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

--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,'張三',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,'張三',23,1);

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

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

INSERTINTO`student`VALUES(4,'趙六',26,2);

SETFOREIGN_KEY_CHECKS=1;

對應(yīng)的sql語句：

SELECT*FROMcard；

SELECT*FROMpersonWHEREid=#{id};

創(chuàng)建PersonMapper接口

publicinterfacePersonMapper{

//根據(jù)id查詢

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

publicabstractPersonselectById(Integerid);

}

使用注解配置Mapper

publicinterfaceCardMapper{

//查詢?nèi)?/p>

@Select("SELECT*FROMcard")

@Results({

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

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

@Result(

property="p",//被包含對象的變量名

javaType=Person.class,//被包含對象的實際數(shù)據(jù)類型

column="pid",//根據(jù)查詢出的card表中的pid字段來查詢person表

one、@One一對一固定寫法

select屬性：指定調(diào)用哪個接口中的哪個方法

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

publicabstractListCardselectAll();

}

測試類

publicclassTest01{

@Test

publicvoidselectAll()throwsException{

//1.加載核心配置文件

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

//2.獲取SqlSession工廠對象

SqlSessionFactorysqlSessionFactory=newSqlSessionFactoryBuilder().build(is);