Question

我有一个查询，它应该使用同一数据库中的两个表之间的连接函数来创建一个临时表。服务器。查询运行时没有语法错误，但问题是结果为空。我还在学习SQL，所以我很难搞清楚这个问题。

select *, volume/ case when National_Avg=0 then 1 else National_Avg end as FPD_Renewals 

from ( 

select convert(decimal(10,0), COUNT(srf_borrower)*1.8) as Volume, year(datecompleted) as cal_year, month(datecompleted) as cal_month
from database1.dbo.datafile
where month(datecompleted) = month(dateadd(month,-1,current_timestamp))
      and year(datecompleted) = year(dateadd(month,-1,current_timestamp))
group by month(datecompleted), year(datecompleted))a

join(select cal_date, National_Avg
from database1.dbo.calendar
where cal_date = month(dateadd(month,-1,current_timestamp))
    AND cal_date  = year(dateadd(month,-1,current_timestamp)))b

    on a.cal_year = b.cal_date and a.cal_month = b.cal_date

我希望查询显示上个月的结果，因此当表1中的年份和月份与表2中的年份匹配时，表1中的数据类型为＆＃39; datetime＆＃39;表2中的数据类型是＆＃39; datetime＆＃39;同样。在我的日历表中，我有几个列，我有两个选项是＆＃39; year＆＃39;和＆＃39;月＆＃39;列，但这些数据类型不是＆＃39; datetime＆＃39;和sql给我一个转换错误。

表2中的一些示例数据：

Table 1
ID cal_month cal_year     cal_date  fy_date    Tor Mtl National_avg
1   January   2018      2018-01-01 2018-01-01  22  22       22

我做错了什么，我该如何解决？谢谢大家

Answer 1

我认为第二个子查询只需要抽出月份和年份，这样你就可以比较苹果和苹果。

SELECT
  *,
  volume / CASE
    WHEN National_Avg = 0 THEN 1
    ELSE National_Avg
  END AS FPD_Renewals

FROM (SELECT
  CONVERT(decimal(10, 0), COUNT(srf_borrower) * 1.8) AS Volume,
  YEAR(datecompleted) AS cal_year,
  MONTH(datecompleted) AS cal_month
FROM database1.dbo.datafile
WHERE MONTH(datecompleted) = MONTH(DATEADD(MONTH, -1, current_timestamp))
AND YEAR(datecompleted) = YEAR(DATEADD(MONTH, -1, current_timestamp))
GROUP BY MONTH(datecompleted),
         YEAR(datecompleted)) a

JOIN (SELECT
  cal_date,
  National_Avg,
  YEAR(cal_date) AS cal_year,
  MONTH(cal_date) AS cal_month
FROM database1.dbo.calendar
WHERE MONTH(cal_date) = MONTH(DATEADD(MONTH, -1, current_timestamp))
AND YEAR(cal_date) = YEAR(DATEADD(MONTH, -1, current_timestamp))) b

  ON a.cal_year = b.cal_year
  AND a.cal_month = b.cal_month

SQL语法 - 查询问题

1 个答案: