Populate other column value based on previous row value using t-sql

Question

Hi All,
I have one table with 6 columns, let say ID1, ID2,status, EnteredDate,NewValue, Old Value. Where ID1 is the primary key field
 ID1       ID2       status             EnteredDate        NewValue      
Old Value
  1          XYZ       New              07/12/2012           
ABC               null
  2          XYZ       Renewal        08/19/2012            DEF               
null
  3          XYZ       Cancel           10/21/2012            GHI               
null
  4          ZYX       New              09/15/2012           
BDF               null
  5          ZYX       Cancel           10/21/2012            MNS             
null
  6          MBS       New              05/29/2012           
EXP               null
  7          SBX        New              05/29/2012           
SKS               null
  8          SBX        Renewal        06/21/2012            QSR              
SKS
Basically I need a sql query which should populate Output as below. Status=New will always have old date compared to Renewal and Cancel and also OldValue field will be null always for status=New
Output:
 ID1       ID2       status           EnteredDate        NewValue      
Old Value     Row_Num(based on ID1,ID2,Entereddate)
  1          XYZ       New              07/12/2012           
ABC               null                 1
  2          XYZ       Renewal        08/19/2012            DEF               
ABC                2
  3          XYZ       Cancel           10/21/2012            GHI               
DEF                 3
  4          ZYX       New              09/15/2012           
BDF               null                   1
  5          ZYX       Cancel           10/21/2012            MNS              
BDF                 2
  6          MBS       New              05/29/2012           
EXP               null                  1
  7          SBX        New              05/29/2012           
SKS               null                  1
  8          SBX        Renewal        06/21/2012            QSR              
SKS                2
Thanks in Advance, its very urgent. Pls send me the query ASAP.
RH
sql

Answer 1

Hi,
In case of you are using SQL 2012, you can use new built-in function like LAG, try this;
USE tempdb
GO
CREATE TABLE dbo.Test
ID1 int PRIMARY KEY
, ID2 char(3) NOT NULL
, Status varchar(20) NOT NULL
, EnteredDate date NOT NULL
, NewValue char(3) NOT NULL
, OldValue char(3) NULL
GO
INSERT INTO dbo.Test
(ID1, ID2, Status, EnteredDate, NewValue, OldValue)
VALUES
(1, 'XYZ', 'New', '07/12/2012', 'ABC', null)
, (2, 'XYZ', 'Renewal', '08/19/2012', 'DEF', null)
, (3, 'XYZ', 'Cancel', '10/21/2012', 'GHI', null)
, (4, 'ZYX', 'New', '09/15/2012' ,'BDF', null)
, (5, 'ZYX', 'Cancel', '10/21/2012', 'MNS',null)
, (6, 'MBS', 'New', '05/29/2012', 'EXP', null)
, (7, 'SBX', 'New', '05/29/2012', 'SKS', null)
, (8, 'SBX', 'Renewal', '06/21/2012', 'QSR', 'SKS')
WITH cte
AS
(SELECT ID1, ID2, Status, EnteredDate, NewValue, OldValue
, ROW_NUMBER() OVER(PARTITION BY ID2 ORDER BY ID2) Row_Num
, LAG(NewValue, 1, 0) OVER(PARTITION BY ID2 ORDER BY ID2) NewOldValue
FROM dbo.Test)
SELECT ID1, ID2, Status, EnteredDate, NewValue
, NULLIF(NewOldValue, '0') NewOldValue, Row_Num
FROM cte
ORDER BY ID1, ID2;
Dinesh Priyankara
http://dinesql.blogspot.com/
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