2018年3月21日
mask
摘要： 1 select 2 count(1) as cnt 3 from ( 4 select '0' as flag union all 5 select 'a' as flag union all 6 select null as flag 7 ) t0 8 where flag 0 9 ; 10 11 select 12 ... 阅读全文
posted @ 2018-03-21 09:58 chenzechao 阅读(159) 评论(0) 推荐(0)