SQL学习之每日一题

After executing the following code, how many rows remain in each table (Countries, Cities and Buyers)?

CREATE TABLE Test.Countries(CountryId INT PRIMARY KEY)
INSERT INTO Test.Countries VALUES(1),(2),(3)
GO
CREATE TABLE Test.Cities( CityId INT PRIMARY KEY
  ,CountryId INT REFERENCES Test.Countries ON DELETE CASCADE);
INSERT INTO Test.Cities VALUES(1,1),(2,1),(3,2) 
GO
CREATE TABLE Test.Buyers(CustomerId INT PRIMARY KEY
 ,CityId INT REFERENCES Test.Cities ON DELETE CASCADE);
 INSERT INTO Test.Buyers  VALUES(1,1),(2,1),(3,2)
GO
 DELETE FROM Test.Countries WHERE CountryId = 1

CREATE TABLE Test.Countries(CountryId INT PRIMARY KEY) --建表<国家>
INSERT INTO Test.Countries VALUES(1),(2),(3)--添加3条记录：1,2,3
GO
CREATE TABLE Test.Cities(
CityId INT PRIMARY KEY,
CountryId INT REFERENCES Test.Countries ON DELETE CASCADE);--建表<城市>，添加删除级联<删除[国家]，会删除相应的[城市]>

INSERT INTO Test.Cities VALUES(1,1),(2,1),(3,2) --添加三条记录：国家1有2个城市，国家2一个城市
GO
CREATE TABLE Test.Buyers(
CustomerId INT PRIMARY KEY,
CityId INT REFERENCES Test.Cities ON DELETE CASCADE);--建表<客户>，添加删除级联<删除[城市]，会删除城市里相应的[客户]>
INSERT INTO Test.Buyers VALUES(1,1),(2,1),(3,2)--添加三条记录：城市1有2个客户，城市2有1个客户
--现在的情况：
国家1 [城市1(客户1,客户2)，城市2(客户3)]
国家2 [城市3]
国家3
GO
DELETE FROM Test.Countries WHERE CountryId = 1

删除国家1,第一行全没了，客户清空，城市剩1个，国家剩2个

From the data below, I need to get records with the FirstName of Kim or Tim only. Frame the query, applying a wildcard search on the FirstName column.

SELECT FirstName FROM Employees
WHERE FirstName like '[KT]im'