sql - 加入 2 个表并获得巧合的总和

Question

来自注册用户的表格：

• id_user
• id_location
• 姓名

来自位置的表格：

• id_location
• 姓名

我需要知道每个位置有多少用户。像这样的东西：

• 华盛顿：455
• 佛罗里达州：185
• 德克萨斯州：914

它尝试了这种方法，但结果肯定有总和错误。

SELECT location.name,user.id_user FROM user
INNER JOIN location ON user.id_location = location.id_location
WHERE user.id_profile !=0 GROUP BY location.id_location ORDER BY location.name

Answer 1

SELECT location.id_location, location.name, COUNT(user.id_user) AS UserCount
FROM user 
INNER JOIN location ON user.id_location = location.id_location 
WHERE user.id_profile !=0 
GROUP BY location.id_location, location.name
ORDER BY location.name 

id_location如果您以某种方式具有相同的位置名称，但位置 ID 不同， 我已将其添加到查询中。

Answer 2

你真的很接近，你只需要做一个COUNT：

SELECT location.name, COUNT(user.id_user) UserCount 
FROM user
INNER JOIN location 
ON user.id_location = location.id_location
WHERE user.id_profile !=0 
GROUP BY location.name
ORDER BY location.name