来获得日期差

Question

喜亚姆有两列

PR_PurchaseRequestHistory  

1)uid       
2)POUID      
3)PRUID       
4)PRDUID      
5)CreatedDtTm     
6)ModifiedDtTM 

PO_PurchaseOrderDetails 
1)uid 
2)PRUid 
3)RespondedDtTm 
4)ModifiedDtTm 
5)CreatedDtTm 

（唯一PRUId）被分配给每一个新的请求和订单时POUId为PRUId.I需要获得该ID的平均日期的差异生成特定月份

我认为这使问题明确 请帮助我。我已经在这个问题很长一段时间

Answer 1

SELECT AVG(HOUR(TIMEDIFF(PO_PurchaseOrderDetails.RespondedDtTm, PR_PurchaseRequestHistory.CreatedDtTm))) 
FROM PR_PurchaseRequestHistory 
INNER JOIN PO_PurchaseOrderDetails ON PR_PurchaseRequestHistory.PRUID = PO_PurchaseOrderDetails.PRUID 
WHERE MONTH(PR_PurchaseRequestHistory.CreatedDtTm) = 3 -- March 
AND YEAR(PR_PurchaseRequestHistory.CreatedDtTm) = 2011