用于计算分组值的SQL列

Question

我希望显示作业表中按customer_id分组的作业数量是多少。如果approval_date不为null，则确定批准。因此，如果总共有12个工作岗位，我想表明7个工作被批准了。如果批准日期为空，则不批准该作业。

select   
  c.customer_name
  ,count(*) as counts
  , -- i want to add a column here that tells me which jobs have (j.approval_date is not null)
from job j
join customer c on j.customer_id = c.customer_id
group by c.customer_name

下面的代码给出了语法错误：

,count(approval_date is not null) as is_approved

Answer 1

你可以使用条件总和：

DataGrid