CROSS JOIN和之间有什么区别INNER JOIN?
交叉加入:
SELECT
Movies.CustomerID, Movies.Movie, Customers.Age,
Customers.Gender, Customers.[Education Level],
Customers.[Internet Connection], Customers.[Marital Status],
FROM
Customers
CROSS JOIN
Movies
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内部联接:
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
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哪一个更好,为什么我会使用其中一个?