[求助]构造sql语句时发生蹊跷的错误

我的思路是这样的，构造字符串sCalcFields，以此作为sql查询语句的字段。但运行时发生错误，信息如下：

Error Executing Database Query.

Query Of Queries syntax error.
Encountered "(. Incorrect Select Statement, Expecting a 'FROM', but encountered '(' instead, A select statement should have a 'FROM' construct.

498 : <cfquery name="rsS" dbtype="query">
499 : select #sCalcFields# from rs
500 : </cfquery>

SQL select sum(yns_1) as yns_1,sum(yns_1c) as yns_1c,sum(yns_1a) as yns_1a,decode(sum(yns_1),0,null,sum(yns_1a)/sum(yns_1))*100 as yns_1p,sum(yns_2) as yns_2,sum(yns_2c) as yns_2c,sum(yns_2a) as yns_2a,decode(sum(yns_2),0,null,sum(yns_2a)/sum(yns_2))*100 as yns_2p from rs

但是，我在toad中，直接执行
select sum(yns_1) as yns_1,sum(yns_1c) as yns_1c,sum(yns_1a) as yns_1a,decode(sum(yns_1),0,null,sum(yns_1a)/sum(yns_1))*100 as yns_1p,sum(yns_2) as yns_2,sum(yns_2c) as yns_2c,sum(yns_2a) as yns_2a,decode(sum(yns_2),0,null,sum(yns_2a)/sum(yns_2))*100 as yns_2p from （在此将rs替换为具体的select语句），是没有问题的。

另还发现，如果将sCalcFields构造成不使用decode的字符串：如
sum(yns_1) as yns_1,sum(yns_1c) as yns_1c,sum(yns_1a) as yns_1a,sum(yns_1a)/sum(yns_1)*100 as yns_1p,sum(yns_2) as yns_2,sum(yns_2c) as yns_2c,sum(yns_2a) as yns_2a,sum(yns_2a)/sum(yns_2) as yns_2p
程序就能正常运行了，求助各位大侠，怎么回事呢？我还是希望使用decode判断的