The ROW NUMBER function is a SQL ranking function that gives each new record in a partition a sequential rank number. When the SQL Server ROW NUMBER function finds two similar values in the same partition, it assigns each of them a separate rank number.
The row number() function can be used to generate a unique number (an ID variable). It can also be used to assign a grouping variable to each observation. Let's add a variable called Session to the practise dataset. Each session consists of one positive and one bad day that are the most recent in date.
The analytic function ROW NUMBER is used to calculate the number of rows in a row. It assigns a unique number to each row to which it is applied (either each row in the partition or each row returned by the query), starting with 1 in the ordered sequence indicated in the order by clause.
The sequential number assigned to each returned row during query execution is ROWNUM. ROW NUMBER assigns a number to each row based on the order in which they appear within a collection of rows. The function ROW NUMBER returns a numeric number.
