MySQL COUNT(), AVG() and SUM() Functions

MySQL COUNT(), AVG() and SUM() Functions

These are aggregate functions in MySQL used to perform calculations on a set of values and return a single result.

📌 1. COUNT() Function

The COUNT() function is used to count the number of rows that match a specific condition.

✅ Syntax:

Example Table: students

✔ Example: Count All Rows

Output:

✔ Example: Count Non-NULL Values in marks

Output:

📌 2. AVG() Function

The AVG() function returns the average value of a numeric column.

✅ Syntax:

✔ Example: Find Average Marks

Note: AVG() ignores NULL values.

✔ AVG() with Condition

📌 3. SUM() Function

The SUM() function returns the total sum of numeric values in a column.

✅ Syntax:

✔ Example: Total Marks

Output:

(76 + 85 + 90 + 92 = 343 → NULL ignored)

✔ SUM() with Condition

🧠 Combine All Functions

🎯 Summary Table