MySQL COUNT(), AVG(), and SUM() Functions: Definition, Syntax, and Examples

student_id	name	gender	city	age	score	course_id	email	phone_number
1	Alice	Female	Delhi	20	85	101	NULL	1234567890
2	Bob	Male	Mumbai	22	75	NULL	bob@email.com	NULL
3	Charlie	Male	Delhi	21	95	102	NULL	NULL
4	David	Male	Bangalore	23	65	101	david@email.com	NULL
5	Eve	Female	Mumbai	20	80	103	NULL	NULL
6	Frank	Male	Delhi	22	90	103	NULL	NULL
7	Alice	Female	Mumbai	19	60	102	NULL	NULL

1. `COUNT()` – Count Rows

The COUNT() function returns the total number of rows that match a condition.

Syntax:

SELECT COUNT(column_name)
FROM table_name
WHERE condition;

The following SQL statement finds the number of students:

Example

SELECT COUNT(*) AS total_students FROM students;

Try it yourself

Note

NULL values are ingnored.

2. `AVG()` – Calculate Average Value

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

Syntax:

SELECT AVG(column_name)
FROM table_name
WHERE condition;

The following SQL statement finds the average score of all students:

Example

SELECT AVG(score) AS avg_score FROM students;

Try it yourself

3. `SUM()` – Calculate Total Value

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

Syntax:

SELECT SUM(column_name)
FROM table_name
WHERE condition;

The following SQL statement finds the sum of the "score" fields in the "Students" table:

Example

SELECT SUM(score) AS total_score FROM students;

Try it yourself

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

Demo Database

1. COUNT() – Count Rows

Syntax:

2. AVG() – Calculate Average Value

Syntax:

3. SUM() – Calculate Total Value

Syntax:

MySQL Aggregate Functions: `COUNT()`, `AVG()`, and `SUM()`

1. `COUNT()` – Count Rows

2. `AVG()` – Calculate Average Value

3. `SUM()` – Calculate Total Value