【LeetCode】0175. Combine Two Tables

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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


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.

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。

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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