AVG
The AVG() function in SQL is an aggregate function that returns the average value of a numeric column. It calculates the sum of values in a column and then divides it by the count of those values.
Syntax:
SELECT AVG(column_name)
FROM table_name;
This statement will return the average value of the specified column.
Example Usage of AVG:
Consider the following table Orders:
| OrderID | CustomerID | Quantity |
|---|---|---|
| 1 | A | 30 |
| 2 | A | 40 |
| 3 | B | 20 |
| 4 | B | 60 |
| 5 | C | 50 |
| 6 | C | 10 |
Let's calculate the average quantity in the Orders table:
SELECT AVG(Quantity) AS AvgQuantity
FROM Orders;
The result is 35. This value is the average of all Quantity values in the table.
It's also possible to group the average function by one or more columns. For example, to find the average quantity of order per customer, we can write:
SELECT CustomerID, AVG(Quantity) as AvgQuantity
FROM Orders
GROUP BY CustomerID;
It will calculate the average quantity for each customer and display the result along with the associated customer's ID.
Note: The
AVG()function works only with numeric data types (INT,FLOAT,DECIMAL, etc.). It will return an error if used with non-numeric data types.