CROSS JOIN
和INNER JOIN
之间有什么区别?
CROSS JOIN:
SELECT
Movies.CustomerID, Movies.Movie, Customers.Age,
Customers.Gender, Customers.[Education Level],
Customers.[Internet Connection], Customers.[Marital Status],
FROM
Customers
CROSS JOIN
Movies
INNER JOIN:
SELECT
Movies.CustomerID, Movies.Movie, Customers.Age,
Customers.Gender, Customers.[Education Level],
Customers.[Internet Connection], Customers.[Marital Status]
FROM
Customers
INNER JOIN
Movies ON Customers.CustomerID = Movies.CustomerID
哪一个更好?我为什么要用这两个呢?