查詢其他記錄的SQL子查詢語法

Question

我需要在表中找到具有0保費的策略，但如果具有相同保單號的另一個策略具有保費，則不需要。這裏是我的僞代碼：

select * from tblPolicies where premium = 0 
(but not if anther record has the same policyNumber and premium <> 0) 

我知道這是可怕的，但我迷路了，這是我能拿出最好的！

Answer 1

可能的查詢1：

SELECT M.* FROM tblPolicies AS M 
WHERE premium = 0 AND policyNumber NOT IN 
(
    SELECT S.policyNumber 
    FROM tblPolicies AS S 
    WHERE S.policyNumber = M.policyNumber 
    AND S.premium <> 0 
) 

可能的查詢2：

SELECT SA.* FROM 
(
    SELECT M.* FROM tblPolicies AS M 
    WHERE premium = 0 
) AS SA 
INNER JOIN tblPolicies AS SB 
ON SA.policyNumber = SB.policyNumber 
WHERE SB.premium <> 0 

可能的查詢3：

SELECT * FROM tblPolicies AS SA 
INNER JOIN tblPolicies AS SB 
ON SA.policyNumber = SB.policyNumber 
WHERE SA.premium = 0 AND SB.premium <> 0 

Answer 2

select p_no from 
(select p_no, sum(premium) as tot_prem from policy group by p_no) as pol 
where tot_prem>0; 

p_no->premium_no

策略 - >策略表