GROUP BY
- Meaning: Group similar rows together and then apply aggregate functions (like SUM, AVG, COUNT).
- Think of it like: Making groups in a classroom. Example: Students grouped by subject, then calculate total or average marks per subject.
Example:
| Student | Subject | Marks |
|---|---|---|
| Raju | Math | 80 |
| Pooja | Math | 90 |
| Amit | Science | 70 |
| Neha | Science | 60 |
sql
SELECT Subject, AVG(Marks)
FROM Students
GROUP BY Subject;
Output:
- Math → 85
- Science → 65
So GROUP BY = Group then summarize.
ORDER BY
- Meaning: Arrange rows in ascending (ASC) or descending (DESC) order.
- Think of it like: Sorting your exam results – highest to lowest marks, or alphabetically by name.
Example:
sql
SELECT Student, Marks
FROM Students
ORDER BY Marks DESC;
Output:
- Pooja → 90
- Raju → 80
- Amit → 70
- Neha → 60
So ORDER BY = Sorting (like arrange in queue).
Quick Analogy (Cricket Example):
Imagine a cricket match scoreboard.
- GROUP BY → Group by Team and show total runs of each team.
- ORDER BY → Sort players by runs scored (highest to lowest).
Super-Simple Recap for Freshers:
- GROUP BY = Make groups (used with aggregate functions like SUM, AVG).
- ORDER BY = Sort the result (ASC/DESC).