You are a database developer for an 
automobile dealership. You are designing 
a database to support a

  web site that will be used for purchasing 
automobiles. A person purchasing 
an automobile from the web

  site will be able to customize his 
or her order by selecting the model 
and color.

  The manufacturer makes four different 
models of automobiles. The models can 
be ordered in any one of
five colors. A default color is 
assigned to each model.

  The models are stored in a table 
named Models, and the colors are 
stored in a table named Colors. These
tables are shown in the exhibit.
You need to create a list of all possible 
model and color combinations. 
Which script should you use?
（分析，这里是要列出车型和颜色的所有组合，
而根本不涉及条件，）

A SELECT m.ModelName, c.ColorName

  FROM Colors AS c FULL OUTER JOIN Models AS m

  ON c.ColorID = m.ColorID

  ORDER BY m.ModelName, c.ColorName （分析，
这里是全外连接，因为车型表里只有一个颜色ID（缺省），
那么这里就只有8（4+4）条记录选出来了）

B SELECT m.ModelName, c.ColorName

FROM Colors AS c CROSS JOIN Models AS m

ORDER BY m.ModelName, c.ColorName 
（答案在此，交叉连接就是列出所有的可能组合
20（5*4）条记录，根本不用条件）

C SELECT m.ModelName, c.ColorName
FROM Colors AS m INNER JOIN Colors AS c
ON m.ColorID = c.ColorID
ORDER BY m.ModelName, c.ColorName 
（分析，内连接，缺省的情况下只能查出4条记录）

D SELECT m.ModelName, c.ColorName
FROM Colors AS c LEFT OUTER JOIN Models AS m 
（分析，左外连接，缺省情况下只能查出5条记录）
ON c.ColorID = m.ColorID
UNION
SELECT m.ModelName, c.ColorName
FROM Colors AS c RIGHT OUTER JOIN Models AS m 
（分析，右外连接，缺省情况下只能查处4条记录）
ON c.ColorID = m.ColorID
  ORDER BY m.ModelName, c.ColorName

E SELECT m.ModelName
FROM Models AS m
UNION
SELECT c.ColorName 
(分析，这个是合并连接，是查询不匹配的行。 
应该是 8-4=4 条记录，就是车型表里不存在的颜色）
FROM Colors AS c
ORDER BY m.ModelName