Row number
The rownumber function returns an integer number which is different for each row of the result set.
The syntax of the function is
rownumber()
Example
# Get top 10 regions by per capita sales
SELECT
    rownumber() AS rank,
    region,
    sales/population AS per_capita_sales
  FROM sales
  ORDER BY per_capita_sales DESC
  LIMIT 10;
  
    Statistics for MySQL