MySQL Ranking Functions

MySQL provides several ranking functions that allow you to assign a rank to rows within a result set based on specified criteria. These functions are commonly used in scenarios where you need to determine the rank, position, or order of rows in a result set. Some of the key ranking functions in MySQL are:

1. ROW_NUMBER(): Assigns a unique integer value to each row within the result set based on a specified order. This function is not available in MySQL, but you can emulate it using session variables.

   SET @row_number = 0;
   SELECT (@row_number := @row_number + 1) AS row_number, column1, column2
   FROM your_table
   ORDER BY column1;

2. RANK(): Assigns a rank to each row within the result set, allowing for duplicate ranks in case of tied values.

   SELECT RANK() OVER (ORDER BY column1) AS rank, column1, column2
   FROM your_table;

3. DENSE_RANK(): Similar to RANK(), but it doesn’t leave gaps in case of tied values. If two rows have the same rank, the next rank is incremented without gaps.

   SELECT DENSE_RANK() OVER (ORDER BY column1) AS dense_rank, column1, column2
   FROM your_table;

4. NTILE(): Divides the result set into the specified number of roughly equal parts and assigns a group number to each row.

   SELECT NTILE(4) OVER (ORDER BY column1) AS quartile, column1, column2
   FROM your_table;

These ranking functions are part of the Window Functions category in MySQL and provide powerful tools for analyzing and ranking data within a result set. They are often used for tasks like calculating top N records, determining percentiles, and finding the highest or lowest values in a dataset. Please note that these functions are available in MySQL 8.0 and later versions. If you are using an older version of MySQL, you may need to implement ranking logic manually using SQL queries and variables.