How to use the SQL ROW_NUMBER function?

In SQL, the ROW_NUMBER() function is used to assign a unique number to each row in a result set. It is often used for sorting or filtering the result set.

The syntax of the ROW_NUMBER() function is as follows:

ROW_NUMBER() OVER (ORDER BY column1, column2, ...)

The ORDER BY clause is used to specify the columns by which the data should be sorted, and it can be used to sort by multiple columns. For example:

SELECT column1, column2, ..., ROW_NUMBER() OVER (ORDER BY column1, column2, ...)
FROM table_name

Here is an example using the ROW_NUMBER() function to sort the records in the “Employees” table and return the row number for each record:

SELECT EmployeeID, FirstName, LastName, ROW_NUMBER() OVER (ORDER BY LastName, FirstName) AS RowNumber
FROM Employees

This will return a result set that includes the EmployeeID, FirstName, LastName, and RowNumber columns for each record. The RowNumber column will be assigned a unique row number based on the sorting of LastName and FirstName.