MySQL连接查询构造

我有两张桌子：工作和活动。 作业由零个或多个活动组成

JOBS (id,client_name,job_cost):

1, 'Kelly, Peter', '139.00'


ACTIVITIES (id,job_id,activity_name,activity_cost):

1, 1, 'Activity A', '40.00'

2, 1, 'Activity B', '59.00'

3, 1, 'Activity C', '40.00'

如何编写查询以检索以下字段：

DESIRED OUTPUT FIELDS:

job_id, client_name, job_cost, total_cost_of_activities, number_of_activities

作为MySQL的任何帮助都不是我的强项

SELECT
  JOBS.*,
  SUM(ACTIVITIES.activity_cost) AS total_cost_of_activities,
  COUNT(ACTIVITIES.id) AS number_of_activities
FROM
  JOBS
  INNER JOIN ACTIVITIES on ACTIVITIES.job_id=JOBS.id
GROUP BY JOBS.id

编辑：我还没有在MySQL上工作过。我假设MySQL的基本SQL语法保持不变

SELECT j.id, j.client_name, j.job_cost, 
COUNT(a.id) AS number_of_activities, SUM(activity_cost) as total_cost_of_activities
FROM Jobs AS j
INNER JOIN Activities AS a ON j.id = a.job_id
GROUP BY j.id, j.client_name, j.job_cost

---

请注意：数字类型不应存储为

VARCHAR

s（您用引号将它们写出来）。为了提高速度和节省空间，您应该使用数字数据类型，如DECIMAL。

+1，因为您希望在一个查询中执行此操作，而不是在多个查询和服务器端代码中执行此操作。我认为您需要一个

分组依据

too@yshavit谢谢，

ERR 0xDEADBEEF:复制粘贴作业不完整

SELECT j.id, j.client_name, j.job_cost, 
COUNT(a.id) AS number_of_activities, SUM(activity_cost) as total_cost_of_activities
FROM Jobs AS j
INNER JOIN Activities AS a ON j.id = a.job_id
GROUP BY j.id, j.client_name, j.job_cost