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我正在查看作業表中由customer_id分組的許多作業是否被批准。如果approval_date不爲空,則確定審批。因此,如果總共有12份工作,我想表明7份已被批准。如果批准日期爲空,則該作業未獲批准。下面用於計算分組值的SQL列
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
的代碼提供了語法錯誤:
,count(approval_date is not null) as is_approved
計數(approval_date)? –
不完全 - 批准日期不能爲空,才能將工作視爲已批准。 –
'COUNT(表達式)'只能計算值,NULL就像[這裏]討論的一樣(https://stackoverflow.com/questions/26368794/why-arent-nulls-counted-in-countcolumnname)。 – HABO