Question

SELECT datediff(Contract_Start_Date,Contract_End_Date) FROM testdata;

此查询始终返回null

我的约会对象是

Time ID        Date
TIME_101    2011-12-12
TIME_102    2011-12-13
TIME_103    2011-12-14
TIME_104    2011-12-15
TIME_105    2011-12-16
TIME_106    2011-12-19
TIME_107    2011-12-20
TIME_108    2011-12-21
TIME_109    2011-12-22

和

Contract ID Contract Start Date Contract End Date
CON_001          TIME_101         TIME_1248
CON_002          TIME_102         TIME_1249
CON_003          TIME_103         TIME_1250
CON_004          TIME_104          TIME_1251
CON_005          TIME_105         TIME_1252
CON_006          TIME_106         TIME_1253

我需要获取合同开始日期和合同结束日期之间的差异

Answer 1

确保您正在比较日期表示而不是代码（'2011-12-12'，而不是'TIME_101';您是否在两个表之间执行正确的连接？）并且使用正确的方法将这些表示解析为日期格式（在您的问题中不会出现在任何地方）。

Answer 2

用于计算日期差异的T-SQL查询：

select Contract_ID, datediff(Day,Contract_Start_Dt,Contract_End_Dt) as [Datediff]
from 
(
    select TD.Contract_ID,
    (
        select T1.[Date]
        from table1 T1
        where T1.Time_ID = TD.Contract_Start_Date
     )  as Contract_Start_Dt 
    ,
    (   select T1.[Date]
        from table1 T1
        where T1.Time_ID = TD.Contract_End_Date 
    )  as Contract_End_Dt
    FROM testdata TD 
) as T

[编辑：在T-SQL查询后按月分组的开始日期和结束日期之间存在差异，以获得合同计数]

select COUNT(*) 
from 
(
select Contract_ID,Contract_Start_Dt,Contract_End_Dt, datediff(Day,Contract_Start_Dt,Contract_End_Dt) as [Datediff]
from 
(
    select TD.Contract_ID,
    (
        select T1.[Date]
        from table1 T1
        where T1.Time_ID = TD.Contract_Start_Date
     )  as Contract_Start_Dt 
    ,
    (   select T1.[Date]
        from table1 T1
        where T1.Time_ID = TD.Contract_End_Date 
    )  as Contract_End_Dt
    FROM testdata TD 
) as T) as T1
where [Datediff]>0 -- case when there exists a difference between two dates
group by MONTH(Contract_Start_Dt)

希望这有帮助!!!

datediff函数始终返回null

2 个答案: