Explaining ROW_NUMBER(), RANK(), and DENSE_RANK() Functions in Oracle

When it comes to Oracle SQL, ROW_NUMBER(), RANK(), and DENSE_RANK() are commonly used window functions for generating unique row numbers within a specified range. Here is a brief explanation of the differences between these functions:

• ROW_NUMBER(): This function is used to assign a unique sequential integer to each row in the result set. It will increment the row number for each row, regardless of duplicates.
• RANK(): RANK() function assigns a unique rank to each row based on the specified ORDER BY clause. If there are ties in the ranking, the same rank is assigned to those rows, and the next rank is adjusted accordingly.
• DENSE_RANK(): DENSE_RANK() function also assigns a unique rank to each row based on the specified ORDER BY clause. The key difference from RANK() is that it does not leave gaps in the ranking when there are ties. The ranks are continuous without any gaps.

When using these functions in Oracle, understanding the subtle differences between ROW_NUMBER(), RANK(), and DENSE_RANK() can help you achieve the desired outcome in your SQL queries.