Building #11 is undergoing a major renovation. Implement a query to close all requests from apartments in this building.
--TABLE Apartments
+-------+------------+------------+ | AptID | UnitNumber | BuildingID | +-------+------------+------------+ | 101 | A1 | 11 | | 102 | A2 | 12 | | 103 | A3 | 13 | | 201 | B1 | 14 | | 202 | B2 | 15 | +-------+------------+------------+
-- TABLE Buildings
+------------+-----------+---------------+---------------+ | BuildingID | ComplexID | BuildingName | Address | +------------+-----------+---------------+---------------+ | 11 | 1 | Eastern Hills | San Diego, CA | | 12 | 2 | East End | Seattle, WA | | 13 | 3 | North Park | New York | | 14 | 4 | South Lake | Orlando, FL | | 15 | 5 | West Forest | Atlanta, GA | +------------+-----------+---------------+---------------+
-- TABLE Tenants
+----------+------------+
| TenantID | TenantName | +----------+------------+ | 1000 | Zhang San | | 1001 | Li Si | | 1002 | Wang Wu | | 1003 | Yang Liu | +----------+------------+
-- TABLE Complexes
+-----------+---------------+ | ComplexID | ComplexName | +-----------+---------------+ | 1 | Luxuary World | | 2 | Paradise | | 3 | Woderland | | 4 | Dreamland | | 5 | LostParis | +-----------+---------------+
-- TABLE AptTenants
+----------+-------+
| TenantID | AptID | +----------+-------+ | 1000 | 102 | | 1001 | 102 | | 1002 | 101 | | 1002 | 103 | | 1002 | 201 | | 1003 | 202 | +----------+-------+
-- TABLE Requests
+-----------+--------+-------+-------------+ | RequestID | Status | AptID | Description | +-----------+--------+-------+-------------+ | 50 | Open | 101 | | | 60 | Closed | 103 | | | 70 | Closed | 102 | | | 80 | Open | 201 | | | 90 | Open | 202 | | +-----------+--------+-------+-------------+
这道题让我们更新11号Building，将其所有的Apartment的状态改为Closed，那么我们需要在Requests表中改，该表是状态和Apartment的关系，所以还需要在Apartments表里找和Building的关系，我们用Update和Set关键字来更新Requests表，参见代码如下：
UPDATE Requests SET Status = 'Closed' WHERE AptID IN (SELECT AptID FROM Apartments WHERE BuildingID = 11);
运行结果：
+-----------+--------+-------+-------------+ | RequestID | Status | AptID | Description | +-----------+--------+-------+-------------+ | 50 | Closed | 101 | | | 60 | Closed | 103 | | | 70 | Closed | 102 | | | 80 | Open | 201 | | | 90 | Open | 202 | | +-----------+--------+-------+-------------+
本文转自博客园Grandyang的博客，原文链接：租房之三[CareerCup] 15.3 Renting Apartment III ，如需转载请自行联系原博主。
