mysql中列转行

通过group_concat（）函数来实现
select group_concat(name) from table group by type
select group_concat(name separator ';') from table group by type
select group_concat(name separator ';') from table where column like '%sys%'
当确定列数时可采用下面sql将列转为行
SELECT userid,
SUM(IF(`subject`='语文',score,0)) as '语文',
SUM(IF(`subject`='数学',score,0)) as '数学',
SUM(IF(`subject`='英语',score,0)) as '英语',
SUM(IF(`subject`='政治',score,0)) as '政治' 
FROM tb_score 
GROUP BY userid

1.mapper.xml文件

<?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="com.cykj.reports.mapper.main.PerfCsMapper">

    <select id="findPercsByPrjAndBuild" resultType="java.util.HashMap">
        select
            apk_package_name 'apkName',
            ROUND(avg(apk_start_time),2) 'stAvg',
            ROUND(max(apk_start_time),2) 'stMax',
            ROUND(min(apk_start_time),2) 'stMin',
            group_concat(test_round) 'roundList',
            group_concat(apk_start_time) 'stList'
        from
            tb_project p inner join tb_build b on p.id = b.prj_id
            INNER JOIN tb_test_event e on b.id = e.build_id
            inner join tb_report_perf_coldstart pf on e.id = pf.test_event_id
        <where>
            e.testtype_id = 1
            <if test="param1 != null and param1 != ''">
                and p.prj_name = #{param1}
            </if>
            <if test="param2 != null and param2 != ''">
                and b.build_name = #{param2}
            </if>
        </where>
        group by apk_package_name
    </select>

</mapper>

2.mapper文件

package com.cykj.reports.mapper.main;

import java.util.List;
import java.util.Map;

public interface PerfCsMapper {
    List<Map<String,String>> findPercsByPrjAndBuild(String prjName, String bdName);
}

3.ServiceImpl.java

package com.cykj.reports.service.impl;

import com.cykj.reports.mapper.main.PerfCsMapper;
import com.cykj.reports.service.PerfCsService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

@Service
public class PerfCsServiceImpl implements PerfCsService {
    @Autowired
    private PerfCsMapper perfCsMapper;

    @Override
    public List<Map<String, String>> findPercsByPrjAndBuild(String prjName, String bdName) {
        return perfCsMapper.findPercsByPrjAndBuild(prjName,bdName);
    }
}

4.Service文件

package com.cykj.reports.service;

import java.util.List;
import java.util.Map;

public interface PerfCsService {
    List<Map<String,String>> findPercsByPrjAndBuild(String prjName, String bdName);
}

5.Controller文件

package com.cykj.reports.controller;

import com.cykj.reports.domain.main.*;
import com.cykj.reports.service.*;
import com.cykj.reports.util.ColToRowUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Controller
public class PerformanceController {
    @Autowired
    private PerfCsService perfCsService;

    //performance页面对应的下拉选所产生的相应数据显示
    @RequestMapping(value = "/performance")
    public String smoke(Model model){
       
        //7.查询最新projectName和及相关最新buildName对应的perfColdstart信息
        List<Map<String,String>> csMaps = perfCsService.findPercsByPrjAndBuild(prjName,bdName);
        //重组map集合
        List<Map<String, String>> csList = ColToRowUtil.getCsRowList(csMaps);

        model.addAttribute("csList",csList);
        return "performance";
    }

    //project改变时
    @RequestMapping(value = "/findPerfDataByProject")
    @ResponseBody
    public Map<String,Object> findDataByProject(@RequestParam("project") String project){
        Map<String,Object> map = new HashMap<>();
     
        //7.查询最新projectName和及相关最新buildName对应的perfColdstart信息
        List<Map<String,String>> csMaps = perfCsService.findPercsByPrjAndBuild(project,bdName);
        List<Map<String, String>> csList = ColToRowUtil.getCsRowList(csMaps);
        map.put("csList",csList);

        return map;
    }

    //build改变时
    @RequestMapping(value = "/findPerfDataByProjectAndBuild")
    @ResponseBody
    public Map<String,Object> findDataByProjectAndBuild(@RequestParam("project")String project, @RequestParam("build")String build){
        Map<String,Object> map = new HashMap<>();
        
        //7.查询最新projectName和及相关最新buildName对应的perfColdstart信息
        List<Map<String,String>> csMaps = perfCsService.findPercsByPrjAndBuild(project,build);
        List<Map<String, String>> csList = ColToRowUtil.getCsRowList(csMaps);
        map.put("csList",csList);

        return map;
    }

}

6.ColToRowUtil.java

package com.cykj.reports.util;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ColToRowUtil {

    public static List<Map<String,String>> getCsRowList(List<Map<String,String>> maps){
        List<Map<String,String>> mapList = new ArrayList<>();

        for(Map<String,String> m:maps) {
            Map<String, String> map = new HashMap<>();

//            System.out.println(m.get("bmType"));
            map.put("apkName",m.get("apkName"));
            map.put("stAvg",String.valueOf(m.get("stAvg")));
            map.put("stMax",String.valueOf(m.get("stMax")));
            map.put("stMin",String.valueOf(m.get("stMin")));

//            System.out.println(m.get("roundList"));
            String[] roundLists = m.get("roundList").split(",");
//            System.out.println(m.get("scoreList"));
            String[] stLists = m.get("stList").split(",");
            for(int i=0;i<roundLists.length;i++){
                map.put(roundLists[i],stLists[i]);
            }

            /*for (Map.Entry<String, String> entry : map.entrySet()) {
                System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue()+"");
            }*/

//            System.out.println(map.size());
            mapList.add(map);
        }

        return mapList;
    }

}

参考链接： https://www.cnblogs.com/xiaoxi/p/7151433.html