Mybatis嵌套子查询动态SQL编写实践

本文主要是介绍Mybatis嵌套子查询动态SQL编写实践，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

《Mybatis嵌套子查询动态SQL编写实践》：本文主要介绍Mybatis嵌套子查询动态SQL编写方式,具有很好的参考价值,希望对大家有所帮助,如有错误或未考虑完全的地方,望不吝赐教...

前言

MyBATis的xml文件编写动态SQL是从mapper中获取传入的参数，但是如果是嵌套的子查询中，子查询动态SQL所需的参数不能像常规的那样直接从mapper中获取，因为嵌套子查询中能获取的传参仅能来源于主查询中的结果，如下文所示，即如何去解决这一问题

一、实体类

1、主类

import io.swagger.v3.oas.annotations.media.Schema;
import lombok.*;
import Java.time.LocalDateTime;
import java.util.List;

@Schema(description = "返回结果实体 Response VO")
@Data
@EqualsAndHashCode(callSuper = true)
@ToString(callSuper = true)
public class MainDataRespVO extends MainDataBaseVO {

    @Schema(description = "主键ID")
    private Long id;

    @Schema(description = "创建时间")
    private LocalDateTime createTime;

    @Schema(description = "子类详情列表")
    private List<SubDataRespVO> subDataList;
}

2、子类

import io.swagger.v3.oas.annotations.media.Schema;
import lombok.*;
import java.time.LocalDateTime;

@Schema(description = "管理后台 - 子类实体信息 Response VO")
@Data
@EqualsAndHashCode(callSuper = true)
@ToString(callSuper = true)
public class SubDataRespVO extends SubDataBaseVO {

    @Schema(description = "主键ID")
    private Long subDataId;

    @Schema(description = "创建时间"D)
    private LocalDateTime createTime;
}

二、Mapper

List<MainDataRespVO> getMainDataList( @Param("localDateStart") String localDateStart,
                                            @Param("localDateEnd") String localDateEnd,
                                            @Param("shiftType") String shiftType,
                                            @Param("userId") Long userId);

三、XML

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="xxx.MainDataMapper">

    <resultMap id="selectShiftDateList" type="xxx.MainDataRespVO">
        <id property="id" column="id"/>
        <result property="workDate" ckhfnwaYhayolumn="work_date"/>
        <result property="createTime" column="create_time"/>
        <colljsection property="subDataList"
                    javaType="list"
                    ofType="xxx.vo.SubDataRespVO"
                    select="selectSubDataList"
                    column="{id=id, shiftType=shiftType, userId=userId}">
        </collection>
    </resultMap>

    <resultMap id="selectSubDataListMap" type="xxx.vo.SubDataRespVO">
        <result property="subDataId" column="id"/>
        <result property="createTime" column="create_time"/>
    javascript    <result property="userName" column="userName"/>
        <result property="shiftType" column="shift_type"/>
        <result property="userId" column="user_id"/>
        <result property="shiftDateId" column="shift_date_id"/>
    </resultMap>

    <select id="selectSubDataList" resultMap="selectSubDataListMap">
        select
  php      t2.id,
        t2.shift_date_id,
        t2.shift_type,
        t2.create_time,
        t2.user_id
        from sub_data t2
        where t2.main_data_id = #{id} and t2.deleted = 0
        <if test="shiftType!=null and shiftType != ''">
            and t2.shift_type = #{shiftType}
        </if>
        <if test="userId!=null and userId != ''">
            and t2.user_id =  #{userId}
        </if>
        order by t2.create_time asc
    </select>

    <select id="getMainDataList" resultMap="selectMainDataList">
        select
        t1.id,
        t1.work_date,
        t1.create_time,
        #{shiftType} as shiftType,  <!-- 将外部参数作为常量列 -->
        #{userId} as userId        <!-- 将外部参数作为常量列 -->
        from main_data t1
        where t1.deleted = 0
javascript        <if test="localDateStart!=null and localDateStart != ''">
            and t1.work_date >=  #{localDateStart}
        </if>
        <if test="localDateEnd!=null and localDateEnd != ''">
            and #{localDateEnd} >= t1.work_date
        </if>
        order by t1.work_date asc
    </select>

</mapper>