sql group query with new serial number

In SQL, you can use theROW_NUMBER()function to add a new serial number to each row in the result set. This number is the result of a partition sort based on some sort condition.

Here's a simple example, assuming we have a file namedstudentsof the table, which has two columns:class_idcap (a poem)student_name. We would like to create a serial number for students within the same class according to thestudent_nameSort:

SELECT 
    class_id,
    student_name,
    ROW_NUMBER() OVER (PARTITION BY class_id ORDER BY student_name) AS seq_num
FROM 
    students;

In this query, theROW_NUMBER()The function will provide a serial number for each student within the class, which is sorted alphabetically by the student's name. If you want to sort by other criteria, just add a new value to theORDER BYJust modify it in the clause.