I'm trying to determine the length of time in days between using the AR_Event_Creation_Date_Time for every other row. For example, the number of days between the 1 and 2 row, 3rd and 4th, 5th and 6th etc. In other words, there will be a number of days value for every even row and NULL for every odd row. My code below works if there are only two rows per borrower number but falls down when there are more than two.
SELECT Borrower_Number, Workgroup_Name, FORMAT(AR_Event_Creation_Date_Time,'d','en-us') AS Tag_Date, Usr_Usrnm, DATEDIFF(day, LAG(AR_Event_Creation_Date_Time,1) OVER(PARTITION BY Borrower_Number Order By Borrower_Number), AR_Event_Creation_Date_Time) Diff FROM Control_Mail
Notice the change in 1002092539