CBSE 2026 results are out, Mukul scored a perfect 100/100 in Computer ScienceSee all toppers →
KwickprepKwickprep
Book Demo

KwickClips Databases and SQL · 38 sec · free

Which COUNT counts rows?

Short answer. COUNT(*).

Why is COUNT(marks) smaller?

It ignores NULL values.

Remember

COUNT(*): all rows
COUNT(col): skips NULL

Same table, two counts. Why five and four? Count star counts every row. Count marks skips NULL. Kabir has no marks, so four. Count star counts all rows. Count of a column skips NULL.

This clip is from the full lesson: Aggregate Functions: COUNT, SUM, AVG, MAX and MIN — 6 minutes, with the tables, the quick answers and the whole lesson in text.

Useful for: CBSE Class 9 Computer Applications (165), CBSE Class 12 Computer Science (083), CBSE Class 12 Informatics Practices (065)

More KwickClips from this lesson

Column of marks collapsing into a single total.What does an aggregate function return?39 secOne query returning SUM, AVG, MAX and MIN together.Can one SELECT use four aggregates?42 secComparison of AVG when a mark is NULL and when it is 0.Does AVG treat NULL as zero?42 sec
Book a free demo classAll free Databases and SQL lessons

Voice-over is AI-generated; the script is written and checked by Kajal Ma'am. Confirm anything you plan around against your official board document. We never ask for a password or an OTP.

Want a plan that actually fits your board dates?

Ask Kajal Ma'am directly, 20+ years teaching computer science. Free demo class first, no payment.

Talk to Kajal Ma'am on WhatsApp

Or see the Class 12 Computer Science course →

Studying outside India?

We coach CBSE, IGCSE & international students across the globe, one-to-one, in your local time zone.

Visit International →