计算列

Question

我想在表格中添加一列来计算两个日期之间的周数，这两个日期在另外两列中。列是：

[DateStart] [date] NULL,
[DateEnd] [date] NULLNumOfWeeks,
[NumOfWeeks] [int] 

如果结束日期为NULL，则计算结果应为StartDate与当前日期之间的周数。

干杯， 凯文。

Answer 1

简单：

ALTER TABLE [table] ADD
[NumOfWeeks] AS DATEDIFF(week, DateStart, COALESCE(DateEnd, GETDATE())

Answer 2

以下是Case方法也有效......

ALTER TABLE Timeslots ADD
[NumOfWeeks] AS DATEDIFF(week, DateStart, CASE when DateEnd IS NULL THEN GETDATE() Else DateEnd END)