Query to enter serial number on following pattern of data..

Data Pattern

• Column1: A A A B B C C C
•  NewCol : 1  2  3  1 2  1  2  3
•  KeyCol  : There shoud be a primary key col in the required table(SomeTable)

ALTER TABLE SomeTable ADD NewCol INTEGER NULL

GO

UPDATE SomeTable
 SET NewCol =
 (SELECT COUNT(*)
 FROM SomeTable AS S
 WHERE Column1=SomeTable .Column1
 AND KeyCol<=SomeTable .KeyCol)