SQL Server：获取日期范围和天数

Question

I have 4 columns (two columns filter) and one column date and one column flag. For a combination of column 1 and column 2, and the open flag, I want to find the open date, the close date and number of days where it was open.

Here is my example and what I want to find with SQL is with the blue/grey color

Answer 1

如果您已经有两个可用的日期作为OpenDate和CloseDate在您的情况下，您可以使用DATEDIFF()函数，如下所示。

Select DATEDIFF(DAY, OpenDate, CloseDate) as NumberOfOpenDays from YourTable

Answer 2

This looks a gaps-and-islands problem -- but the islands are already defined by opendt (and perhaps col1 and col2 ).

So, you can just use row_number() :

select row_number() over (partition by col1, col2, opendt order by effectivedt)