【MyBatis嵌套查询】MyBatis使用‘association’标签实现嵌套查询

返回类结构(内部类)

public class testDto{

	private Integer id;
	private String name;
	private List<Child> childList;

	public static class Child{
        private Integer id;
	    private String name;
 }
 
}

resultMap编写

<resultMap id="TestDto" type="com.x.y.testDto">
        <id property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <association property="childList" column="id" select="queryChildList" javaType="java.util.ArrayList" />
</resultMap>

‘select’为嵌套查询的SQL的ID名称
‘column’为要带入的某列的值

<select id="queryTestDto" resultMap="TestDto">
        SELECT id,name FROM test
</select>

<select id="queryTestDto" resultMap="com.x.y.testDto$Child">
        SELECT id,name FROM test
        WHERE parent_id=#{id}
</select>