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  • [LeetCode]-DataBase-Combine Two Tables

    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


    需求:简单的表连接

    查询:sql

    CREATE TABLE Person(
    PersonId TINYINT UNSIGNED auto_increment PRIMARY KEY,
    FirstName varchar(20),
    LastName varchar(20)
    )ENGINE=MyISAM CHARSET=utf8;
    CREATE TABLE Address(
    AddressId TINYINT UNSIGNED auto_increment PRIMARY KEY,
    PersonId TINYINT UNSIGNED,
    City VARCHAR(20),
    State VARCHAR(20)
    )ENGINE=MyISAM CHARSET=utf8;


    SELECT t1.FirstName,t1.LastName,t2.City,t2.State
    FROM Person t1
    LEFT JOIN Address t2 ON t1.PersonId=t2.PersonId




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  • 原文地址:https://www.cnblogs.com/lianliang/p/5303037.html
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