MySQLでテーブルをピボットする方法

考えるべき3つのことがあります1）最大の束を動的に生成する方法（2の場合はケースをグループ化するために何かを割り当てる-この場合は変数を使用して行番号を生成します3）いくつかの役職には次のものが含まれます列ヘッダーの生成のために削除した空白

set @sql = 
            (select concat('select ', gc,            ' from 
             (select name,job_title,
                if (job_title <> @p, @rn:=1 ,@rn:[email protected]+1) rn,
                @p:=job_title p
                from t
                cross join (select @rn:=0,@p:=null) r
                order by job_title
              ) s group by rn;') from
            (select 
                group_concat('max(case when job_title = ', char(39),job_title ,char(39),' then name else char(32) end ) as ',replace(job_title,char(32),'')) gc
                from
                (
                select distinct job_title from t
                ) s
                ) t
             )
;           

このSQLコードを生成します

select max(case when job_title = 'Fireman' then name else char(32) end ) as Fireman,
        max(case when job_title = 'Driver' then name else char(32) end ) as Driver,
        max(case when job_title = 'Analyst' then name else char(32) end ) as Analyst,
        max(case when job_title = 'Postman' then name else char(32) end ) as Postman,
        max(case when job_title = 'Research Manager' then name else char(32) end ) as ResearchManager
         from 
             (select name,job_title,
                if (job_title <> @p, @rn:=1 ,@rn:[email protected]+1) rn,
                @p:=job_title p
                from t
                cross join (select @rn:=0,@p:=null) r
                order by job_title
              ) s group by rn;

動的SQLに送信できるもの

prepare sqlstmt from @sql;
execute sqlstmt;
deallocate prepare sqlstmt;

結果

+---------+--------+---------+---------+-----------------+
| Fireman | Driver | Analyst | Postman | ResearchManager |
+---------+--------+---------+---------+-----------------+
| Sam     | Tomas  | Lisa    | Marcus  | Mary            |
| Peter   | Chen   | Stephan |         |                 |
|         |        | Albert  |         |                 |
+---------+--------+---------+---------+-----------------+
3 rows in set (0.00 sec)