如何解决总和，长度和分组依据的问题

Question

字段合同是文本，值是用“，”分隔的字符串。

查询：

select sum( if( length(dapps.contracts) = 
       sum(length(replace(dapps.contracts,',',''))) , 1 , length(dapps.contracts) 
     - sum(length(replace(dapps.contracts,',',''))) ) ) as f1 
  from dapps 
 group by id 

显示：

Error in query (1111): Invalid use of group function 

需要一级查询

此查询工作正常

select sum(f1)
from (
 select if( length(dapps.contracts) = 
        sum(length(replace(dapps.contracts,',',''))) , 1 , length(dapps.contracts) 
      - sum(length(replace(dapps.contracts,',',''))) ) as f1 
   from dapps 
  group by id
) tb1​

需要查询而无需子查询