sql多字段求和并作为sql查询条件的实现[MSSQL防范]

下面就sql多字段求和并作为sql查询条件的办法举行了阐明,供您参考,但愿对您学习sql查询方面有所帮忙.

做一个字段求和的小sql查询,查询一个表中,字段1,字段2和字段3之和大于0的后果,故写了以下的SQL语句.

有一点要注意的是,在Where字句中,不能有自己运算后得到的字段.

sqlstr = "SELECT W.ID,W.Weather,greenColor,(SELECT redColor+greenColor+blueColor FROM Weather N WHERE N.ID = W.ID) AS AllValue FROM Weather W WHERE (SELECT redColor+greenColor+blueColor FROM Weather N WHERE N.ID = W.ID)>0 ORDER BY ID";

即以下的SQL语句是行不通的,说是"至少一个参数没有被指定值".

sqlstr = "SELECT W.ID,W.Weather,greenColor,(SELECT redColor+greenColor+blueColor FROM Weather N WHERE N.ID = W.ID) AS AllValue FROM Weather W WHERE AllValue >0 ORDER BY ID";