一个字符串转数字的小功能

with t as 
(
  select "-" as col1   --isnumeric("-")这里会判断为数字，所以不能用
  union all
  select "1" as col1 
  union all 
  select "2" as col1 
  union all 
  select "3.4" as col1 
  union all 
  select "s" as col1 
)
select col1, convert(numeric(10,4), 
--                case WHEN isnumeric(col1)=1 then col1 else 0*1.0 end 
                case WHEN PATINDEX("%[^0-9|.|-|+]%",col1)=0
                  THEN col1 
                  ELSE 0*1.0
                end
                ) 
        as cc from t