做一個字段求和的小sql查詢，查詢一個表中，字段1，字段2和字段3之和大于0的結果，故寫了如下的SQL語句。

有一點要注意的是，在Where字句中，不能有自己運算后得到的字段。

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";

即如下的SQL語句是行不通的，說是"至少一個參數(shù)沒有被指定值"。

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";