SQL 与 & OR

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

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

LastName	FirstName	Address	City
Hansen	Ola	Timoteivn 10	Sandnes
Svendson	Tove	Borgvn 23	Sandnes
Svendson	Stephen	Kaivn 18	Sandnes

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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：

LastName	FirstName	Address	City
Svendson	Tove	Borgvn 23	Sandnes

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：

LastName	FirstName	Address	City
Svendson	Tove	Borgvn 23	Sandnes
Svendson	Stephen	Kaivn 18	Sandnes

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：

LastName	FirstName	Address	City
Svendson	Tove	Borgvn 23	Sandnes
Svendson	Stephen	Kaivn 18	Sandnes