心得:
題目要求找出Person
表內所有人員的地址,就算是空的也無所謂,所以不用理會Address
表內是否有Person
表的資料,這題必須使用LEFT JOIN
來關聯。
問題:
Table:
Person
12345678 +-------------+---------+| Column Name | Type |+-------------+---------+| PersonId | int || FirstName | varchar || LastName | varchar |+-------------+---------+PersonId is the primary key column for this table.Table:
Address
123456789 +-------------+---------+| 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:
1 FirstName, LastName, City, State
答案:
1 2 3 4 5 |
# Write your MySQL query statement below SELECT a.FirstName, a.LastName, b.City, b.State FROM Person AS a LEFT JOIN Address AS b ON a.PersonId = b.PersonId |
參考: