新建表：
"Persons" 表：
Id_P LastName FirstName Address City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York
3 Carter Thomas Changan Street Beijing
"Orders" 表：
Id_O OrderNo Id_P
1 77895 3
2 44678 3
3 22456 1
4 24562 1
查询语句： key
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons, Orders
WHERE Persons.Id_P = Orders.Id_P
结果：
Carter Thomas 77895
Carter Thomas 44678
Adams John 22456
Adams John 24562
查询语句： join
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons
INNER JOIN Orders
ON Persons.Id_P = Orders.Id_P
结果：
Carter Thomas 77895
Carter Thomas 44678
Adams John 22456
Adams John 24562
2018-04-26 11:33:41