mysql仿oracle的decode效果查询 |
本文标签:decode,效果查询 以下代码在MYSQL中测试通过,MSSQL应该能跑通,未测试 。 复制代码 代码如下: #创建表如下 create temporary table tmp (a int, b int ,c int); insert into tmp VALUES (1,10,1),(10,10,2),(10,100,2); #mysql执行 select sum(case when c = 1 then A else B end) from tmp #oracle执行 select sum(decode(c,1,a,b)) from tmp #普通联合查询 select sum(d) from ( select a as d from tmp where c=1 union select b as d from tmp where c=2 ) |