The SELECT statement goes through each row of the “questions” table and checks if it meets the conditions you specify. The problem appears to be in the conditions.
The syntax: table_name[column_name] will return the entire column as a list. So when you write questions[Unique ID], AppSheet will return the entire “Unique ID” column for every check on every row.
You probably want to check the value of “Unique ID” for that specific row. You can do that by writing
The conditions in your SELECT statement are getting into more advanced use of formulas. Typically, the conditions of a SELECT statement will check each row against some static value. For example [_THISROW].[Color] = “Red”. However, in your example, the conditions are checking each row against a value in another table.
It can be done, but it is a challenging place to start if you’re still getting familiar with SELECT statements. If you’d like to give it a shot, then you’ll need to apply the same concepts to the masterDatabase[ID] part of your conditions. This is currently returning the entire “ID” column. Try taking the same concepts and using them to select a specific value from the “ID” column of the “masterDatabase” table.