mysql动态sql 整理多个字段

原始表：

整理后的表：

方案一（动态sql）：

BEGIN
    #Routine body goes here...
    DECLARE v1 int(3);
    DECLARE v2 int(3);
    #DECLARE v3 VARCHAR(15);
    

    #DECLARE vcompany VARCHAR(30);
    #DECLARE vname VARCHAR(30);

    DECLARE vcol VARCHAR(30);
    DECLARE tmp_sql VARCHAR(3000);
    DECLARE vid int(3);


    set v1 = 1;
    WHILE v1 <= 11993 DO
        set v2=2;
        #if v2 <=27 THEN 
        WHILE v2 <=27  DO

            set @v3=CONCAT('l',v2);
            set @vcompany='';
            set @vname='';
            #set @vid='';
            
            SET @l_sql=CONCAT_ws(' ',
                'select company_name,',@v3,
                'into @vcompany,@vname',
                'from for_xun_cha where id =',v1);
            SET @sql=@l_sql;
            prepare stmt from @sql;
            execute stmt;

                #select company_name,l2 into vcompany,vname from for_xun_cha where id=v2;
            if LENGTH(trim(@vname)) > 0 THEN
                INSERT into tmp(company,name) VALUES(@vcompany,@vname);
                #INSERT into tmp(company,name) VALUES(vcompany,tmp_sql);
            end if; 
            set v2 = v2+1;
        #end if;
        end WHILE;
        set v1 = v1 + 1;
    END WHILE;

    
END

方案二（先合并各列，再用游标处理）：

BEGIN
DECLARE Done INT DEFAULT 0;
DECLARE n int ; -- 最大列 27
DECLARE companyName VARCHAR(20) ;-- 公司名称
DECLARE personNames VARCHAR(1000);-- 员工名称
DECLARE personName VARCHAR(10);

DECLARE _cur CURSOR FOR select company_name ,CONCAT_WS(",",l2,l3,l4,l5,l6,l7,l8,l9,l10,l11,l12,l13,l14,l15,l16,l17,l18,l19,l20,l21,l22,l23,l24,l25,l26,l27) from for_xun_cha;

OPEN _cur;
    FETCH _cur INTO companyName,personNames;
    REPEAT
    IF NOT Done THEN
         test:    WHILE(n<=27) DO
            set personName=SUBSTRING_INDEX(SUBSTRING_INDEX(personNames,',',n),',',-1);
                if  ISNULL(personName) || LENGTH(trim(personName))<1 THEN
                        LEAVE test;
                ELSE
                    INSERT INTO temp1 VALUES (companyName,personName);
                END IF;
            set n=n+1;
            end while;
    end IF;
set n = 1;
    FETCH NEXT FROM _cur INTO companyName,personNames;
    UNTIL Done END REPEAT;

-- set personName="";
-- set personNames="";
CLOSE _cur;
END