Use IFNULL to replace NULL values in your data with a more suitable or meaningful value. This can be helpful when you want to avoid displaying NULLs in your charts or when you need a specific value for further calculations.
Sample usage
Syntax
Parameters
input_expression
The expression to evaluate. You can use any valid expression as the input_expression.
null_result
The result to return if input_expression is null. If input_expression is not null, IFNULL returns the input_expression. You can use any valid expression as the input_expression.
Example
Calculate the average discount given to your customers, including orders that received no discount. However, your application sometimes represents "no discount" as null rather than 0.
The formula AVG(Discount) won't include null discounts. You'll need to convert those nulls to zero. To do this, create a new field called, for example, Discount No Nulls:
This formula can be read, "If the Discount field is null, return 0, otherwise return Discount."
You can then calculate the average discount including orders with no discount: