If you are used to working with Excel, you know that all you need is IFERROR() function to avoid any issues with dividing by 0. Also adding a blank to a number is not creating any issues in Excel. In SQL, however, its not that straight forward, you need to remember to differentiate between ISNULL() and NULLIF() functions. They sound very similar so many people constantly confuse them interchangeably.
When to use which?
If you are dividing by zero to avoid having an error in your query, you need to use NULLIF() function.
Example:
If you are adding a blank number to another non-blank number, then you need ISNULL() function in order not to have correct non-blank result.
Example:
Maybe this image can be a good trick to remember to use NULLIF() when dividing by Zero, otherwise you are entering the gate of No Life 🙂
