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

The SQL COUNT (), AVG () and SUM () functions are aggregate functions, which are used to perform calculation on multiple rows and return a single value.All aggregate functions by default exclude nulls values before working on the data.

COUNT Function:
COUNT Function is used to return total number of rows that matches a specified criteria.COUNT(*) also considers Nulls and duplicates.

COUNT Function Syntax :

The syntax of the COUNT Function is −

```SELECT COUNT(column-name)
FROM table-name
WHERE condition;
```

AVG() Functions :

AVG Function is used to return average value of rows that matches a specified criteria.AVG() function works only on numeric data types.

AVG() Functions Syntax :

The syntax of the AVG() Functions is −

```SELECT AVG(column-name)
FROM table-name
WHERE condition;
```

SUM() Functions :

SUM Function is used to return total sum of rows that matches a specified criteria. SUM only works on numeric fields. Null values ​​are excluded from the returned result.

SUM() Functions Syntax :

The syntax of the SUM() Functions is −

```SELECT SUM(column-name)
FROM table-name
WHERE condition;
```

SQL COUNT(), AVG() and SUM() Example :

Consider the Customer table with the following records -

1 Aarav 28 Udaipur 28000
2 Vivaan 25 Mumbai 30000
3 Reyansh 28 Chennai 35000
5 Sai 30 Mumbai 27000

COUNT Example:- The following code is an example that will return the total customer IDs in the table.

```SELECT COUNT(CustomerID)
FROM Customer;
```

The result for the respective sql query is as follows −

COUNT(CustomerID)
5

AVG Example:-The following code is an example that will return the average of CustomerSalary in the table.

```SELECT AVG(CustomerSalary)
FROM Customer;
```

The result for the respective sql query is as follows −

AVG(CustomerSalary)
34000

SUM Example:- The following code is an example that will return the SUM of CustomerSalary in the table.

```SELECT SUM(CustomerSalary)
FROM Customer;
```

The result for the respective sql query is as follows −

SUM(CustomerSalary)
170000

Visit :

Discussion