sql列转行

1.需要实现一个单行的统计报表

思路先用一个union查出单列，然后再把单列转成单行

2.实现

SELECT

MAX(CASE WHEN type = 1 THEN num ELSE 0 END) AS 'GeneralCnt',

MAX(CASE WHEN type = 2 THEN num ELSE 0 END) AS 'HistoryCnt'

from (

select '1' as 'type',count(*) as 'num'

from General

union all

select '2' ,count(*)

from History

) tmp