Implementation of MyBatis Mapper Mapper Mapping File Configuration

<!--mybatis-configFile configuration，Aliases can be defined for some classes-->
<!--<typeAliases>
    <typeAlias type="" alias="emp"></typeAlias>
</typeAliases>-->
<!-- typeUse alias in the attribute without using the full path -->
<resultMap  type="emp">
    <id property="empId" column="emp_id"></id>
    <result property="empName" column="emp_name"></result>
    <result property="empSalary" column="emp_salary"></result>
</resultMap>
<select  resultMap="empMapper">
    select * from t_emp
</select>

<!-- Public code -->
<sql >
    <!-- select * from t_emp -->
    select emp_id empId,emp_name empName,emp_salary empSalary from t_emp
</sql>
    
<!--selectTagsidCorrespond to the method name of the interface，resultTypeand return result encapsulationBeanConsistent-->
<select  resultType="">
    <!-- include:Used to load and extract publicsqlStatement，and<sql>Tag correspondence
           refid:fill in<sql>In the tagidproperty-->
    <include ref></include>
    where emp_id=#{empId}
</select>
    
<select  parameterType="Emp" resultType="emp">
    <!-- 引入Public code -->
    <include ref></include>
    <!-- whereLabel:onewhere条件Statement，Usually and<if>Label混合使用 -->
    <where>
        <!-- ifLabel:执行one判断Statement，成立才会执行Label体内的sqlStatement,test:写上条件判断Statement
        Notice:这里每oneifTry to add it beforeand，如果你是第one条件，The framework will help you automaticallyandIntercept，
            If it's the secondifCan't be omittedand-->
        <if test="empId != null and empId != ''">
            and emp_id=#{empId}
        </if>
        <if test="empName != null and empName != ''">
            and emp_name like '%${empName}%'
        </if>
    </where>
</select>

<delete  parameterType="int">
    delete from t_emp where emp_id=#{empId}
</delete>

delete from t_emp where emp_id=?

<select  resultType="">
    select emp_id empId,emp_name empName,emp_salary empSalary from t_emp where emp_name like '%${empName}%'
</select>

Employee selectEmployee(Integer empId);

<select  resultType="">
    select emp_id empId,emp_name empName,emp_salary empSalary from t_emp where emp_id=#{empId}
</select>

int updateEmployee(@Param("empId") Integer empId,@Param("empSalary") Double empSalary);

<update >
    update t_emp set emp_salary=#{empSalary} where emp_id=#{empId}
</update>

int insertEmployee(Employee employee);

<insert >
    insert into t_emp(emp_name,emp_salary) values(#{empName},#{empSalary})
</insert>

int updateEmployeeByMap(Map<String, Object> paramMap);

<update >
    update t_emp set emp_salary=#{empSalaryKey} where emp_id=#{empIdKey}
</update>

/**
 * Statistics of the number of employees
 * @return
 */
Long selectEmployeeCount();

<!--
        Return to simple type:
        resultTypeRepresents the result type:The type returned by the result set,To beMapperThe return value types of corresponding methods in the interface are consistent
    -->
<select  resultType="long">
    select count(emp_id) from t_emp
</select>

Employee selectEmployee(Integer empId);

<!-- Write specificSQLStatement，useidA unique tag for the attributeSQLStatement -->
<!-- resultTypeproperty：Specify the encapsulated query resultJavaThe full class name of the entity class -->
<select  resultType="">
    <!-- MybatisResponsible for takingSQLStatement中的#{} part replaced with "?" placeholder -->    <!-- Set an alias for each field，Let alias andJava实体类中property名一致 -->
    select emp_id empId,emp_name empName,emp_salary empSalary from t_emp where emp_id=#{maomi}
</select>

<!-- On a global scaleMybatisMake configuration -->
<settings>
    <!-- Specific configuration -->
    <!-- You can view the configuration items that can be used from the class -->
    <!-- WillmapUnderscoreToCamelCaseThe attribute is configured astrue，Indicates that automatic mapping camel naming rules are enabled -->
    <!-- Rules require database table fields to be named：word_word -->
    <!-- Rules RequirementsJavaNaming method of entity class attribute name：Camel naming with lowercase initial letter -->
    <setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>

/**
 * Query employee information based on empId and encapsulate the result set into the map
 * @param empId
 * @return
 */
Map selectEmployeeMapByEmpId(Integer empId);

<!--
        returnMaptype:
        resultType表示结果type: that isMapFully qualified name or alias
    -->
<select  resultType="map">
    select * from t_emp where emp_id=#{empId}
</select>

List<Employee> selectAll();

<!-- List<Employee> selectAll(); -->
<select  resultType="">
    select emp_id empId,emp_name empName,emp_salary empSalary from t_emp
</select>

List<Map> selectAllMap();

<select  resultType="map">
    select emp_id empId,emp_name empName,emp_salary empSalary
    from t_emp
</select>

insert into t_order_item(item_name,item_price,item_count,order_id) values(...)

int insertEmployee(Employee employee);

<!-- int insertEmployee(Employee employee); -->
<!-- useGeneratedKeysAttribute literally means“Use the generated primary key” -->
<!-- keyPropertyAttributes can specify the corresponding attribute name of the primary key in the entity class object.，MybatisThe obtained primary key value will be stored in this property -->
<insert  useGeneratedKeys="true" keyProperty="empId">
    insert into t_emp(emp_name,emp_salary)
    values(#{empName},#{empSalary})
</insert>

@Test
public void testSaveEmp() {

    EmployeeMapper employeeMapper = ();
    
    Employee employee = new Employee();
        
    ("john");
    (666.66);
    
    (employee);
    //Print automatically returns the primary key value stored in the object    ("() = " + ());

}

<insert >
    insert into t_emp (emp_name,emp_salary) values (#{empName},#{empSalary})
    <!--
            keyColumn="emp_id"The column name that represents the primary key to query
            keyProperty="empId"Indicates that the query primary key value is assigned toJavaBeanWhich attribute of
            resultType="int"Indicates the result type of the query
            order="AFTER" Indicates that this query is executedinsertBefore or after?IfAFTERAfter the，BEFOREIndicates before
        -->
    <selectKey keyColumn="emp_id" keyProperty="empId" resultType="int" order="AFTER">
        select last_insert_id()
    </selectKey>
</insert>

<insert 
parameterType=""  
databaseId="oracle">
<selectKey order="BEFORE" keyProperty="id"
resultType="integer">
select employee_seq.nextval from dual
</selectKey>    
insert into orcl_employee(id,last_name,email,gender) values(#{id},#{lastName},#{email},#{gender})
</insert>

<insert 
parameterType=""  
databaseId="oracle">
<selectKey order="AFTER" keyProperty="id"
resultType="integer">
select employee_seq.currval from dual
</selectKey>    
insert into orcl_employee(id,last_name,email,gender) values(employee_seq.nextval,#{lastName},#{email},#{gender})
</insert>

<!-- usesettingsrightMybatisSet globally -->
<settings>
    <!-- Willxxx_xxxSuch column names are automatically mapped toxxXxxThe attribute name of the camel-like name -->
    <setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>

<!-- Employee selectEmployee(Integer empId); -->
<select  resultType="">
    select emp_id,emp_name,emp_salary from t_emp where emp_id=#{empId}
</select>

<!--
        Manual mapping:passresultMapTag configuration mapping rules
            1. idproperty:表示这个Manual mapping规则的唯一表示
            2. typeproperty: 表示这个Manual mapping规则是将结果集映射给哪个类的对象，that isJavaBeanFully qualified name of the class
        resultMapLabel中的子Labelthat is一一指定映射规则:
            1. idLabel:Specify the mapping rules for primary keys
            2. resultLabel:Specify mapping rules that are not primary keys
        idLabel和resultLabel的property:
            1. column:The field name of the result set to be mapped
            2. property:To be mappedJavaBean的property名
    -->
<resultMap  type="">
    <id column="emp_id" property="id"/>
    <result column="emp_name" property="name"/>
    <result column="emp_salary" property="salary"/>
</resultMap>
<!--
        existselectLabel中passresultMapproperty来指定使用哪个Manual mapping规则
    -->
<select  resultMap="EmployeeInfoMap">
select * from t_emp where emp_id=#{empId}
</select>

CREATE TABLE `t_customer` (
`customer_id` INT NOT NULL AUTO_INCREMENT,
`customer_name` CHAR(100),
PRIMARY KEY (`customer_id`)
);
CREATE TABLE `t_order` (
`order_id` INT NOT NULL AUTO_INCREMENT,
`order_name` CHAR(100),
`customer_id` INT,
PRIMARY KEY (`order_id`)
);
INSERT INTO `t_customer` (`customer_name`) VALUES ('c01');
INSERT INTO `t_customer` (`customer_name`) VALUES ('c02');
INSERT INTO `t_order` (`order_name`, `customer_id`) VALUES ('o1', '1');
INSERT INTO `t_order` (`order_name`, `customer_id`) VALUES ('o2', '1');
INSERT INTO `t_order` (`order_name`, `customer_id`) VALUES ('o3', '1');
INSERT INTO `t_order` (`order_name`, `customer_id`) VALUES ('o4', '2');
INSERT INTO `t_order` (`order_name`, `customer_id`) VALUES ('o5', '2');

public class Order {
    private Integer orderId;
    private String orderName;
    //Indicate the one-to-one relationship between Order and Customer    private Customer customer;
}

public class Customer {
    private Integer customerId;
    private String customerName;
}

public interface OrderMapper{
    Order findByOrderId(Integer orderId);
}

<!--Global configuration automatically map camel naming-->
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>

    <!--Alias ​​for entity classes-->
    <typeAliases>
        <package name=""/>
    </typeAliases>
        
    <!-- Mapperregister：SpecifyMybatisThe specific location of the map file -->
    <!-- mappersLabel：Configure a specificMapperMapping files -->
    <!-- resourceproperty：SpecifyMapperMapping files的实际存储位置，Here you need to use a classpath root directory
    <mappers>
        <!-- All packagedMapperThe configuration file will be loaded automatically、register，More convenient。 -->
        <package name=""/>
    </mappers>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-////DTD Mapper 3.0//EN"
        "/dtd/">
<mapper namespace="">
    <resultMap  type="Order" autoMapping="true">
        <!-- autoMappingThe property is set totrueTurn on automatic mapping -->
        <association property="customer" javaType="Customer">
            <id column="customer_id" property="customerId"></id>
            <result column="customer_name" property="customerName"></result>
        </association>
    </resultMap>
    <select  resultMap="order">
        select * from t_order o left join t_customer c on o.customer_id=c.customer_id where order_id=#{orderId}
    </select>
</mapper>

public class Customer {
    private Integer customerId;
    private String customerName;
    //One-to-many relationship between customer and order    private List<Order> orderList;
}

public class Order {
    private Integer orderId;
    private String orderName;
}

public interface CustomerMapper {
    Customer findCustomerAndOrders(Integer customerId);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-////DTD Mapper 3.0//EN"
        "/dtd/">
<mapper namespace="">
    <resultMap  type="Customer" >
        <id column="customer_id" property="customerId"/>
        <result column="customer_name" property="customerName"/>
        <collection property="orderList" ofType="Order" autoMapping="true">
            <!--
            Perform one-to-many mapping,usecollectionLabel
                ofTypeAttribute refers toorderListGenerics of
            -->
        </collection>
    </resultMap>
    <select  resultMap="customer">
        SELECT * FROM t_customer c,t_order o WHERE o.customer_id=c.customer_id AND c.customer_id=#{customerId}
    </select>
</mapper>