AND 与 OR

AND and OR join two or more conditions in a WHERE clause.
AND 和 OR 可以在WHERE子句中将两个过多个条件结合起来

The AND operator displays a row if ALL conditions listed are true. The OR operator displays a row if ANY of the conditions listed are true.
当WHERE字句使用AND操作，那么得让AND所关联的所有条件都为真才会将结果显示出来。 使用OR则只需要其中的一个条件符合就可以将该结果显示出来

Original Table (used in the examples)
初始数据表（在举例中使用）

举例

Use AND to display each person with the first name equal to "Tove", and the last name equal to "Svendson":
这句使用了AND，数据要显示那么它的first name必须为"Tove"而且last name必须为"Svendson"。

SELECT * FROM Persons
WHERE FirstName='Tove'
AND LastName='Svendson'

结果：

举例

Use OR to display each person with the first name equal to "Tove", or the last name equal to "Svendson":
这句使用了OR，数据要显示的话那么它所包含的数据里first name为"Tove"或者last name为"Svendon" :

SELECT * FROM Persons
WHERE firstname='Tove'
OR lastname='Svendson'

结果：

举例

You can also combine AND and OR (use parentheses to form complex expressions):
你还可以将AND 与 OR 混合起来使用

SELECT * FROM Persons WHERE
(FirstName='Tove' OR FirstName='Stephen')
AND LastName='Svendson'

结果：

SQL Order By SQL In

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