0 - 3 of 3 tags for LAG

Just recently moved from a windows machine with sql assistant to a mac with studio express, and I'm running into some issues with studio express:

I have the following data;
Account_id   Date           Flag_1
123             012006        ?
123             022006        1
234             012007        1
234             022007        1

I am not positive this is a sliding window problem, but it is my best guess. I would like to show the current rows values and the next row, on the same output record, and then advance to the next recor --, repeat.