mysql - SQL 从两个链接表中选择

Question

我在 MySQL 中有两个表，customer 和 contacts

customer 中的每一行可以在 contacts 中有多个行，并且 contacts.company 将等于 customer.sequence

我如何运行查询来搜索两个表并仅从 customer 表返回结果？

例如，如果我有这个数据:

customer:

sequence = 123
company = Company A

sequence = 321
company = Company B

contacts:

company = 123
forename = John

company = 123
forename = Steve

company = 321
forename = Joe

company = 321
forename = Andy

company = 321
forename = John

然后我搜索 Andy - 它应该返回 Company A

如果我搜索 John，它应该返回 Company A 和 Company B

Answer 1

select
    C.Company
from
    Customer,
    Contacts
where
    Customer.Sequence = Contacts.Company
    and Contacts.Forename = '<your search name goes here>'