题意是选出两个表有相同PersonId的信息。考察SQL LEFT JOIN关键字。
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
# Write your MySQL query statement below
select Person.FirstName, Person.LastName, Address.City, Address.State
from Person left join Address on Person.PersonId = Address.PersonId
