我正在尝试创建一个表，该表提供公司在县内每个地区收到的所有不同查询类型的摘要。
理想情况下，我想要的是以下内容：
面积||主题类型||上个月的Enq ||前12个月的平均enq ||差异百分比
到目前为止，我编写的代码在下面，但我认为这根本不对（我对Oracle SQL相当陌生）。
在此方面的任何帮助将不胜感激。
Select
central_enquiry.enquiry_number,
central_enquiry.enquiry_time,
enquiry_subject.subject_name,
area.area_name
Sum(Case when datediff(month, date, current_timestamp) between 1 and 12 then column_value else 0. End) /12 as avg_column_value,
Sum(Case when datediff(month, date, current_timestamp) = 0 then column_value else 0. end) as sum_current_column_value,
Sum ((100/avg_column_value) * sum_current_column_value) as Percentage_Difference
From
Central_enquiry,
central_site,
enquiry_subject,
area
Where
datediff(month, date, current_timestamp between) 0 and 12
AND enquiry_subject.service_code = central_enquiry.service_code
AND central_site.area_code = area.area_code
AND central_site.site_code = central_enquiry.site_code