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

Assuming SQL Server 2012 or newer...

SELECT
  *,
  LAG(col3) OVER (PARTITION BY col1 ORDER BY col2) AS col4
FROM
  yourTable

If you're on SQL Server 2008 or older...

SELECT
  *,
  (
     SELECT TOP(1) previous.col3
       FROM yourTable   AS previous
      WHERE previous.col1 = yourTable.col1
        AND previous.col2 < yourTable.col2
   ORDER BY previous.col2 DESC
  )
    AS col4
FROM
  yourTable

Answer 2

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.

Answer 3

Use lag() function

select *, lag(col3) over (partition by col1 order by col2) as col4
from table t;

However You can also use subquery if your SQL doesn't have LAG()

select *,   
        (select top 1 col3
         from table
         where col1 = t.col1 and col2 < t.col2
         order by col2 desc
        ) as col4
from table t;

Answer 4

Thank you all for the replies. By using the lag function with partition I got the expected result. I missed to used partition previously and due to that I was getting wrong results.