知识检查

已完成

1.

运行以下查询：SELECT OrderNo, CHOOSE(Status, 'Ordered', 'Shipped', 'Delivered') AS OrderState FROM Sales.Order；对于 Status 值为 2 的行，返回哪个 OrderState 值？

Shipped

已交货

Null

2.

必须返回每个城市中的客户数量。 你该使用哪个查询？

SELECT City, COUNT(*) AS CustomerCount FROM Sales.Customer;

SELECT City, COUNT(*) AS CustomerCount FROM Sales.Customer GROUP BY City;

SELECT City, COUNT(*) AS CustomerCount FROM Sales.Customer ORDER BY City;

3.

必须针对平均价格高于 10.00 的每个类别返回一行。 你该使用哪个查询？

SELECT Category, AVG(Price) FROM Store.Product WHERE AVG(Price) > 10.00;

SELECT Category, AVG(Price) FROM Store.Product GROUP BY Category WHERE AVG(Price) > 10.00;

SELECT Category, AVG(Price) FROM Store.Product GROUP BY Category HAVING AVG(Price) > 10.00;

在检查工作前，必须回答所有问题。