 # SQL SUM() AND AVG()

In SQL, the `SUM()` and `AVG()` functions are used to calculate total and average values in numeric columns.

## SQL SUM() Function

The SQL `SUM()` function is used to calculate the cumulative sum of numeric values in a column. It has the following syntax:

``````SELECT SUM(column_name)
FROM table;``````

Here,

• `SUM` is the function that returns the cumulative sum of numeric values
• `column_name` is the column to which we apply the `SUM` function
• `table` is the name of the table to fetch the data from

For example,

``````--select the sum of amount from Orders table
SELECT SUM(amount) AS total_sales
FROM Orders;``````

Here, the SQL command returns the sum of amount of all orders.

### Example 1: SQL SUM() Function

Let's take a look at another example.

``````--select the sum of the amount of id 4 from orders
SELECT SUM(amount) AS total_of_cus4
FROM Orders
WHERE customer_id = 4;``````

Here, the SQL command returns the total amount to be paid by the customer having `id` 4.

## SQL AVG() Function

The SQL `AVG()` function is used to calculate the average of numeric values in a column. It has the following syntax:

``````SELECT AVG(column_name)
FROM table;``````

Here,

• `AVG` is the function that returns the aggregate of numeric values
• `column_name` is the column to which we apply the `AVG` function
• `table` is the name of the table to fetch the data from

For example,

``````-- get average age of customers
SELECT AVG(age) AS average_age
FROM Customers;``````

Here, the SQL command returns the average age of all customers.

### Example 2: SQL AVG() Function

``````--selects the average amount spent by each customer from the Orders table
SELECT customer_id, AVG(amount) AS average_spends
FROM Orders
GROUP BY customer_id;``````

Here, the SQL command returns the average spending of each customer.