---
title: 【LeetCode】0175. Combine Two Tables
date: 2018-12-19
is_modified: false
disqus: cynthiahackmd
categories:
- "面試刷題"
tags:
- "LeetCode"
- "SQL"
- "Left Join"
---

{%hackmd @CynthiaChuang/Github-Page-Theme %}

<br>

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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<br>

Table: `Person`

| Column Name | Type |
|----------------- |--------- |
| PersonId | int |
| FirstName | varchar |
| LastName | varchar |

PersonId is the primary key column for this table.
<br>

Table: `Address`

| Column Name | Type |
|----------------- |--------- |
| AddressId | int |
| PersonId | int |
| City | varchar |
| State | varchar |

AddressId is the primary key column for this table.

## 解題邏輯與實作
原來 LeetCode 還有出資料庫的題目阿，不過題目看來不多，而且題目也不太難，所以手癢稍微試了一下。

### Left Join
這題看起來就是聯合查表的題目，檢查一下兩張 Table 的欄位，發現 **PersonId** 這欄位兩張表都有且命名也相同，所以我選它直接使用 **Using** 來進行聯合。

SELECT p.FirstName, p.LastName, a.City, a.State 
FROM Person p LEFT OUTER JOIN Address a USING (PersonId);

## 其他連結
1. [【LeetCode】0000. 解題目錄](/x62skqpKStKMxRepJ6iqQQ)

<br><br>

> **本文作者**： 辛西亞．Cynthia
> **本文連結**： [辛西亞的技能樹](https://cynthiachuang.github.io/LeetCode-0175-Combine-Two-Tables) / [hackmd 版本](https://hackmd.io/@CynthiaChuang/LeetCode-0175-Combine-Two-Tables)
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