DBMS

*Aggregate Functions in SQL*

*Aggregate functions* in SQL are used to perform computations on a set of values and
return a single value. They are extremely useful when working with large datasets, as they
help you quickly summarize or extract important information.

The most commonly used aggregate functions in SQL are:

- *COUNT()*
- *SUM()*
- *AVG()*
- *MIN()*
- *MAX()*

These functions allow you to perform a variety of calculations, such as counting records,
summing values, and finding the average, minimum, or maximum values in a dataset.

---

*Common Aggregate Functions:*

1. *COUNT()*
The *COUNT()* function returns the number of rows in a table or a selected group of rows.
It is commonly used to count how many records meet a certain condition.

#### Example:
```sql
SELECT COUNT(*) FROM employees;
```
This query counts the total number of rows in the *employees* table.

2. *SUM()*
The *SUM()* function returns the sum of a set of values, typically used for numerical
columns.

#### Example:
```sql
SELECT SUM(salary) FROM employees;
```
This query calculates the total salary of all employees in the *employees* table.

3. *AVG()*
The *AVG()* function returns the average value of a set of values.

#### Example:
```sql

SELECT AVG(salary) FROM employees;