The following link has an example of an if statement, which you can use to skip a command if the “condition” is false. Conversely, make the condition true if you want to use the command.
I think you can compare if your CSV file is blank using “” to indicate blank.
Use two equal signs to compare if items are same (e.g. ==).
Use an exclamation mark with an equal sign for not same (e.g. !=)