SQLServer2012子查詢練習

 

表結構與數據：https://github.com/XuePeng87/TSQLV4

練習1

練習內容：編寫一個查詢，返回Orders表中能夠查到的活動最後一天的全部訂單

涉及的表：Sales.Orders

輸出的列：orderid, orderdate, custid, empid

正確結果：4行

SELECT orderid, orderdate, custid, empid 
FROM Sales.Orders 
WHERE orderdate = (
	SELECT MAX(orderdate) FROM Sales.Orders
);

練習2

練習內容：編寫一個查詢，返回訂單數量最多的客戶的全部訂單。注意，在一個以上的客戶可能具備相同數量的訂單

涉及的表：Sales.Orders

輸出的列：custid, orderid, orderdate, empid

正確結果：31行

SELECT custid, orderid, orderdate, empid 
FROM Sales.Orders 
WHERE custid = 
(
	SELECT TOP 1 WITH TIES custid FROM Sales.Orders GROUP BY custid ORDER BY COUNT(*) DESC
);

練習3

練習內容：編寫一個查詢，返回在2016年5月1日或以後沒有下訂單的僱員

涉及的表：HR.Employees, Sales.Orders

輸出的列：empid, firstname, lastname

正確結果：4行

SELECT empid, firstname, lastname 
FROM HR.Employees E 
WHERE E.empid NOT IN (
	SELECT O.empid FROM Sales.Orders AS O 
	WHERE O.orderdate >= '20160501'
);

練習4

練習內容：編寫一個查詢，返回有客戶可是沒有僱員的國家

涉及的表：Sales.Customers, HR.Employees

輸出的列：country

正確結果：19行

SELECT DISTINCT country FROM Sales.Customers
WHERE country NOT IN (
	SELECT country FROM HR.Employees
);

練習5

練習內容：編寫一個查詢，返回每一個客戶活動最後一天的全部訂單

涉及的表：Sales.Orders

輸出的列：custid, orderid, orderdate, empid

正確結果：90行

SELECT O1.custid, O1.orderid, O1.orderdate, O1.empid 
FROM Sales.Orders AS O1 WHERE O1.orderdate = (
	SELECT MAX(O2.orderdate) FROM Sales.Orders AS O2 
	WHERE O2.custid = O1.custid
);

練習6

練習內容：編寫一個查詢，返回2015年下過訂單，可是2016年沒有下訂單的客戶

涉及的表：Sales.Customers, Sales.Orders

輸出的列：custid, companyname

正確結果：7行

SELECT custid, companyname FROM Sales.Customers AS C 
WHERE EXISTS (
	SELECT * FROM Sales.Orders AS O1 
	WHERE orderdate BETWEEN '20150101' AND '20151231' AND O1.custid = C.custid 
) AND NOT EXISTS (
	SELECT * FROM Sales.Orders AS O2 
	WHERE orderdate BETWEEN '20160101' AND '20161231' AND O2.custid = C.custid 
);

練習7

練習內容：編寫一個查詢，返回訂購了產品12的客戶

涉及的表：Sales.Customers, Sales.Orders, Sale.OrderDetails

輸出的列：custid, companyname

正確結果：12行

SELECT custid, companyname 
FROM Sales.Customers WHERE custid IN (
	SELECT custid FROM Sales.Orders WHERE orderid IN (
		SELECT orderid 
		FROM Sales.OrderDetails 
		WHERE productid = 12
	)
);

練習8

練習內容：編寫一個查詢，計算每一個客戶及其月度的採購總量

涉及的表：Sales.CustOrders

輸出的列：custid, ordermonth, qty

正確結果：636行

SELECT custid, ordermonth, qty, (
	SELECT SUM(qty) FROM Sales.CustOrders AS O2 
	WHERE O2.custid = O1.custid
	AND O2.ordermonth <= O1.ordermonth
)  AS runqty 
FROM Sales.CustOrders AS O1;