级别15，状态1，行136在需要条件的上下文中指定的非布尔类型表达式，在'）'附近

如果要汇总每个客户的25岁至35岁之间的每个客户最近30天的交易记录，那么您基本上想在汇总之前进行过滤：

SELECT c.customer_Id, SUM(total_amt), DATEDIFF(YEAR, DOB, GETDATE()) as DOB
FROM Customer C JOIN
     (SELECT T.*,
             MAX(tran_date) OVER (PARTITION BY cust_id) as max_tran_date
      FROM Transactions T
     ) T
     ON T.cust_id = C.customer_Id
WHERE DOB >= DATEADD(YEAR, -35, GETDATE()) AND
      DOB < DATEADD(YEAR, -24, GETDATE()) AND
      t.tran_date >= DATEADD(DAY, -30, max_tran_date)
GROUP BY c.customer_Id, DATEDIFF(YEAR, DOB, GETDATE());