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  • LeetCode 175. Combine Two Tables

    分析

    难度 易

    来源

    https://leetcode.com/problems/combine-two-tables/

    SQL LEFT JOIN 关键字

    LEFT JOIN 关键字会从左表 (table_name1) 那里返回所有的行,即使在右表 (table_name2) 中没有匹配的行。

    LEFT JOIN 关键字语法

    SELECT column_name(s)

    FROM table_name1

    LEFT JOIN table_name2

    ON table_name1.column_name=table_name2.column_name

    题目

    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
    解答
    Runtime: 184 ms, faster than 99.52% of MySQL online submissions for Combine Two Tables.
    1 # Write your MySQL query statement below
    2 
    3 select Person.FirstName, Person.LastName,Address.City,Address.State from Person left join Address on Person.PersonId=Address.PersonId order by Person.FirstName;
    博客园的编辑器没有CSDN的编辑器高大上啊
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  • 原文地址:https://www.cnblogs.com/flowingfog/p/9969388.html
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