在SQL中计数-两个表

Question

我有两个表：team（id，name）和users（id，name，team_id）

我想要以下结果：

Team  | Members 
team1 | 10 
team2 | 14 
team3 | 8

我试过了：

SELECT t.name AS 'Team', COUNT(u.email) AS 'Members' FROM teams t INNER JOIN users u ON (u.team_id = t.id) 

但这是行不通的。

Answer 1

您应该使用GROUP BY ，并且别名存在语法错误，请尝试以下操作：

SELECT t.name AS `Team`, COUNT(u.email) AS `Members`
FROM teams t INNER JOIN users u ON (u.team_id = t.id)
GROUP BY t.name -- or t.id

Answer 2

您需要GROUP BY球队名称值：

SELECT t.name AS `Team`, 
       COUNT(u.email) AS `Members` 
FROM teams t 
INNER JOIN users u ON u.team_id = t.id
GROUP BY t.name