You can use an identity field for this, that's what they're for. The logic of the identity(1,1) means that it will start at the number 1 and increment by 1 each time.
Sample data;
CREATE TABLE #OriginalData (Name varchar(4), Description varchar(7)) INSERT INTO #OriginalData (Name, Description) VALUES ('John','student') ,('Dom','teacher')
Make a new table and insert the data into it;
CREATE TABLE #NewTable (Name varchar(4), Description varchar(7), Auto int identity(1,1)) INSERT INTO #NewTable (Name, Description) SELECT Name ,Description FROM #OriginalData
Gives the results as;
Name Description Auto John student 1 Dom teacher 2
If you ran the insert a couple more times your results would look like this;
Name Description Auto John student 1 Dom teacher 2 John student 3 Dom teacher 4 John student 5 Dom teacher 6