如何從單個表中查找訂單大於X的客戶

Question

如何從單個表中查找訂單金額大於$ 2000的客戶姓名？

Customer : 
custName custOrderVal
A        100 
B        200
A        900
C        2400
A        1100
B        8000

select cust.custName from customer cust where cust.custOrderVal > 2000; 將不會顯示正確的數據。 有人可以指導我嗎？

Answer 1

通過使用HAVING子句，像這樣：

SELECT custName
FROM Customer
GROUP BY custName
HAVING SUM(custOrderVal) > 2000

您需要使用GROUP BY來獲取每個客戶的SUM ，然后使用HAVING來限制結果（就像WHERE子句一樣）。

Answer 2

詢問

DECLARE @t TABLE (custName VARCHAR(10),custOrderVal INT)
INSERT INTO @t
VALUES
('A',100), ('B',200),('A',900),('C',2400),
('A',1100),('B',8000),('D',1000),('F',500)

SELECT  CustName
FROM @t
GROUP BY CustName
HAVING SUM(custOrderVal) > 2000

結果集

╔══════════╗
║ CustName ║
╠══════════╣
║ A        ║
║ B        ║
║ C        ║
╚══════════╝

Answer 3

SELECT
  custName,
  SUM(custOrderVal) AS custOrderSum
FROM Customer
GROUP BY custName
HAVING custOrderSum>2000

Answer 4

每當需要過濾分組總計時，都可以使用HAVING子句。

SELECT custName
FROM Customer
GROUP BY custName
HAVING SUM(custOrderVal) > 2000