Product
Hansen, Ola
Printer
Svendson, Stephen
Table
Chair
或者你也可以用JOIN关键字来完成上面的操作:
SELECT Employees.Name, Orders.Product
FROM Employees
INNER JOIN Orders
ON Employees.ID = Orders.ID
INNER JOIN的语法:
SELECT field1, field2, field3
FROM first_table
INNER JOIN second_table
ON first_table.keyfield = second_table.foreign_keyfield
解释:
INNER JOIN返回的结果集是两个表中所有相匹配的数据。
LEFT JOIN的语法:
LEFT JOIN second_table
用”Employees”表去左外联结”Orders”表去找出相关数据:
LEFT JOIN Orders
返回结果:
Name
Svendson, Tove
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