oracle中decode()函数在mysql中怎么改啊，在线等！

[夕阳下的高山]

例如在oracle中是这样写的：select
decode(length(POPEDOM),3,substr(POPEDOM,0,2),4,substr(POPEDOM,0,3),5,substr(POPEDOM,0,2),6,substr(POPEDOM,0,3),7,substr(POPEDOM,0,2),POPEDOM) as type

[QWE470259742]

MYSQL没用过，不过我想case when then应该也是支持的吧： SELECT (CASE length(POPEDOM) WHEN 3 THEN substr(POPEDOM, 0, 2) WHEN 4 THEN substr(POPEDOM, 0, 3) WHEN 5 THEN substr(POPEDOM, 0, 2) WHEN 6 THEN substr(POPEDOM, 0, 3) WHEN 7 THEN substr(POPEDOM, 0, 2) END) AS TYPE FROM DUAL;

[-江沐风-]

引用 1 楼 QWE470259742 的回复:

MYSQL没用过，不过我想case when then应该也是支持的吧： SELECT (CASE length(POPEDOM) WHEN 3 THEN substr(POPEDOM, 0, 2) WHEN 4 THEN substr(POPEDOM, 0, 3) WHEN 5 THEN substr(POPEDOM, 0, 2) WHEN 6 THEN substr(POPEDOM, 0, 3) WHEN 7 THEN substr(POPEDOM, 0, 2) END) AS TYPE FROM DUAL;

没错，oracle的decode()函数可以用MySQL的IF()或者CASE WHEN来替代； oracle的decode()和case when功能上应该是一样的。

[qq_27783159]

select decode(mod((select count(urineiodine) from bs_lowiodinergn_chld_con_srvy order by urineiodine desc) as n,2),1,(n+1)/2*urineiodine,(n/2*urineiodine)+ (n+1)/2*urineiodine ) from bs_lowiodinergn_chld_con_srvy 求帮忙改一下 怎么弄都报错