175 - Combine Two Tables

原创于 2016-03-15 14:24:20 发布 · 339 阅读

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本文提供了一个SQL左连接查询的实例，展示了如何从Person表中获取每个人的详细信息，即使某些记录在Address表中没有匹配项也能显示完整人员名单。

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Table: Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| PersonId    | int     |
| FirstName   | varchar |
| LastName    | varchar |
+-------------+---------+
PersonId is the primary key column for this table.

Table: Address

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| AddressId   | int     |
| PersonId    | int     |
| City        | varchar |
| State       | varchar |
+-------------+---------+
AddressId is the primary key column for this table.

Write a SQL query for a report that provides the following information for each person in the Person table, regardless if there is an address for each of those people:

FirstName, LastName, City, State

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思路分析：

left join

SELECT Person.FirstName, Person.LastName, Address.City, Address.State
FROM Person LEFT JOIN Address 
ON Person.PersonId = Address.PersonId;