Question

我有两张桌子： -

users (username, business_id, etc.)

businesses (business_id, service_type, latitude, longitude, etc.)

我有以下查询可以正常工作：

SELECT username, users.business_id FROM users JOIN businesses 
ON users.business_id = businesses.business_id WHERE service_type = ?

现在，我想在结果中还在“商家”表格中列出“纬度”和“经度”列。我怎么能这样做？

我尝试执行以下操作，但收到错误消息：

SELECT username, users.business_id, businesses.latitude, businesses.longitude 
FROM users, businesses JOIN businesses 
ON users.business_id = businesses.business_id WHERE service_type = ?

获得我需要的结果的正确方法是什么？

Answer 1

你在哪里有两次企业：

FROM users, businesses JOIN businesses

删除第一个，应该像以前一样：

FROM users JOIN businesses

Answer 2

使用显式连接语法：

SELECT username, users.business_id, 
       businesses.latitude, businesses.longitude 
FROM users 
JOIN businesses 
   ON users.business_id = businesses.business_id 
WHERE service_type = ?

您将隐式与显式语法混合使用。因此，, businesses子句中使用的FROM实际上不是必需的。

Answer 3

有一个带有JOIN语法的拼写错误，请尝试以下操作：

SELECT users.username, users.business_id, businesses.latitude, businesses.longitude 
FROM users JOIN businesses ON users.business_id = businesses.business_id 
WHERE service_type = ?

使用join从多个表中选择列

3 个答案: