11.3 COUNT(*) vs COUNT(DISTINCT column)

By Ravindra Bagale Last updated: 31 October 2026

का (Why). ऑर्डर्स मोडणे vs युनिक customers मोडणे — वेगळे प्रश्न.

काय (What). COUNT(*) = रो. COUNT(DISTINCT col) = त्या कॉलममधील युनिक मूल्ये.

कसं (How). SELECT COUNT(*) , COUNT(DISTINCT customer_id) FROM orders;

पायऱ्या

उदाहरण 1 · dataset: raja_coffee

SELECT COUNT(*) AS orders,
       COUNT(DISTINCT customer_id) AS unique_customers,
       COUNT(DISTINCT city) AS unique_cities
FROM orders;

Output

orders	unique_customers	unique_cities
24	8	6

Meaning. ऑर्डर्स vs लोक vs शहरे.

Ravindra Bagale's Tip

COUNT(DISTINCT …) is slower on huge tables — fine on practice sizes.