mybatisPlus 使用mapper多表多连接查询

最新推荐文章于 2025-08-11 11:51:00 发布

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本文深入解析了一段复杂的SQL查询代码，该代码通过多个左连接从不同的表中获取工作信息，包括工作类别、地区、经验和学历等详细数据。通过具体实例，展示了如何在SQL中进行多表关联和条件筛选。

这个问题花了我3个小时，。先上图，以后再解释

<select id="getComJob" parameterType="List" resultType="hashMap">
		select
		job.*,
		jobclass1.name as catname1,
		jobclass2.name as catname2,
		jobclass3.name as catname3,
		province.area_name as addr_province,
		city.area_name as addr_city,
		area.area_name as addr_area,
		jingyan.name as jingyan,
		xueli.name as xueliname
		from
		mj_com_job job
		left join mj_job_class jobclass1 on job.cat1=jobclass1.id
		left join mj_job_class jobclass2 on job.cat2=jobclass2.id
		left join mj_job_class jobclass3 on job.cat3=jobclass3.id
		left join mj_area province on job.provinceid = province.id
		left join mj_area city on job.cityid = city.id
		left join mj_area area on job.three_cityid = area.id
		left join mj_com_class jingyan on job.experience_id=jingyan.id
		left join mj_com_class xueli on job.Education_id=xueli.id
		<where>
			${ew.sqlSegment}
		</where>
	</select>

    public R detail(@RequestParam(value = "jobid") Integer jobid, Model model) {
        QueryWrapper<ComJob> wrapper = new QueryWrapper<>();
        wrapper.eq("job.id",jobid);
        List<ComJob> comJob = jobService.getComJob(wrapper);