这样的SQL如何写

[lovefox_zoe]

select a.areacode as areacode,a.areaName as AreaName,
sub_book_num=(select isNull(sum(b.book_num),0) from cw_book_bill b
where b.areacode=*a.areacode and b.Cz_Date='''+ E_Date +'''),
retail_book_num=(select isNull(sum(c.book_num),0) from cw_retail_bill c
where c.areacode=*a.areacode and c.Pub_date='''+E_date+'''),
sum_book=(sub_Book_Num-retail_Book_num) --此处报错，如何修改呢？
from syspz_areacode a order by a.areacode

想求出SUB_BOOK_NUM和RETAIL_BOOK_NUM的差值

数据库是SQL SERVER

[haishen]

缺空格吧！

[windindance]

不能够对这种字段直接运算的，必须：
sum_book = select isNull(sum(b.book_num),0) from cw_book_bill b
where b.areacode=*a.areacode and b.Cz_Date='''+ E_Date +'''),
-
(select isNull(sum(c.book_num),0) from cw_retail_bill c
where c.areacode=*a.areacode and c.Pub_date='''+E_date+'''),

[windindance]

其实最好sum_book 是在程序中通过计算字段来处理。