从数据类型 varchar 变换为 numeric 时出错

从数据类型 varchar 转换为 numeric 时出错
book05 是decimal(10, 2)  
sql语句报错：从数据类型 varchar 转换为 numeric 时出错。

SQL code

selectbook05=case  when book05 is null or book05='' then '('+ltrim(str(count(*)))+')'  else ltrim(str(book05)) + '('+ltrim(str(count(*)))+')' end from booksgroup by book05 order by book05

SQL code

selectbook05=case  when book05 is null or book05='' --这里出错，book05是数字类型，不能这样then '('+ltrim(str(count(*)))+')'  else ltrim(str(book05)) + '('+ltrim(str(count(*)))+')' end from booksgroup by book05 order by book05selectbook05=case  when book05 is null--这么就行了then '('+ltrim(str(count(*)))+')'  else ltrim(str(book05)) + '('+ltrim(str(count(*)))+')' end from booksgroup by book05 order by book05
[解决办法]
SQL code
selectbook05=case  when isnull(book05,0)=0 then '('+ltrim(str(count(*)))+')'  else ltrim(str(book05)) + '('+ltrim(str(count(*)))+')' end from booksgroup by book05 order by book05
[解决办法]
探讨

book05 是decimal(10, 2)  
sql语句报错：从数据类型 varchar 转换为 numeric 时出错。
SQL code


select
book05=case  when book05 is null or book05='' then '('+ltrim(str(count(*)))+')'  
else 
ltrim(str(book05)) + '('+lt……

[解决办法]
SQL code
selectbook05=case  when book05 is null or book05='' then '('+ltrim(count(*))+')'  else ltrim(book05) + '('+ltrim(count(*))+')' end from booksgroup by book05order by book05