SQL:如何从两个表中获取关系数据? (使用JOIN吗?) [英] SQL: How to get relational data from two tables? (Using JOIN ?)

问题描述

到目前为止，我一直在尝试进行一些交叉关系SQL查询，但没有成功.想知道是否有人可以提供帮助?

I have been experimenting with doing some cross relational SQL queries, without success so far. Wondering if anyone can help?

我有两个感兴趣的表，正在尝试找出我的哪些客户(=公司联系人1)必须处理未完成的项目.这是桌子的结构:

I have two tables of interest and am trying to find out which of my customers (=company contact 1) have to do items outstanding. Here's the table sturcture:

TABLE: CUSTOMERS

ID    |    CUSTOMER_NAME    |    COMPANY_CONTACT
=================================================
1           Bob                     1
2           Billy                   2
3           Susan                   2
4           Ryan                    3
5           Sally                   1

.

TABLE: TO_DOS
ID    |    TASK         |    CUSTOMER_ID
============================================
1          Make Tea                 5
2          Pick flowers             1
3          Do invoices              3
4          Tidy up                  4
5          Drive van                2

理想的输出应该是

CUSTOMER_ID     |   CUSTOMER_NAME  |  TASK
=================================================================
5           Sally         Make Tea
1           Bob           Pick flowers

到目前为止，我已经尝试过了，但是却无济于事:

So far I've tried this but it's not getting me anywhere:

SELECT * FROM TO_DOS
INNER JOIN CUSTOMERS
WHERE CUSTOMERS.COMPANY_CONTACT=1

任何想法都将不胜感激！

Any ideas greatly appreciated!

推荐答案

SELECT CUSTOMERS.ID, CUSTOMERS.CUSTOMER_NAME, TO-DOS.TASK 
FROM TO_DOS
INNER JOIN CUSTOMERS 
ON TO_DOS.CUSTOMER_ID = CUSTOMERS.ID
WHERE CUSTOMERS.COMPANY_CONTACT = 1

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