How to get previous row data in sql server

Question

I would like to get the data from previous row. I have used LAG function but did not get the expected result.

Table:-

col1  col2  col3
ABCD    1   Y
ABCD         


        

Answer 1

If you are on 2008 or earlier, try this:

    select t1.col1, t1.col2, t1.col3, t2.col3 as col4
    from table1 t1
    left join table1 t2 on t1.col1 = t2.col1 and t1.col2 - 1 = t2.col2

the lag() function is the bee's knees, though. Use that, if you can.