Window Functions in MySQL

What are Window Functions?

Example: Running Total

SELECT name, marks,
  RANK() OVER (ORDER BY marks DESC) AS rank_pos,
  AVG(marks) OVER () AS class_avg
FROM students;

PARTITION BY

OVER (PARTITION BY class ORDER BY marks DESC) restarts the calculation for each class — like per-group windows.

Summary

• Window functions compute over related rows without collapsing them.
• Use OVER(); PARTITION BY makes per-group windows.

Window Functions क्या हैं?

Example: Running Total

SELECT name, marks,
  RANK() OVER (ORDER BY marks DESC) AS rank_pos,
  AVG(marks) OVER () AS class_avg
FROM students;

PARTITION BY

OVER (PARTITION BY class ORDER BY marks DESC) हर class के लिए calculation फिर से शुरू करता है — per-group windows की तरह।

सारांश

• Window functions related rows पर compute करते हैं बिना collapse किए।
• OVER() use करें; PARTITION BY per-group windows बनाता है।