I have what I imagine is quite a basic question for you SP folk.
There are two drop-down lists. If the user chooses either of three options out of seven from the top drop-down list, the second field/drop down list appears. If the user picks the other four, the list does not appear.
I know this can be done using validation but what would the =IF function be?
You can't do that with validations. All you can do is have a formula that returns true or false, as to whether that field is valid or not. You can't affect other fields.
If I had to do this, I would put a Script Editor web part on the form and use JavaScript (and Jquery and the SPUtility library from Codeplex) to show/hide the second field in the "onchange" event of the first field.
