FROM THE TUTORIAL: "......Let's say I have an issue with duplicate customers being entered on this table. Let me show you why. I'll add a new customer with the same name it's an existing company and I'll click Save. There's nothing that prevented me from creating that duplicate customer. Let me show you how we can change that. I'm going to right-click on the label for customer name and choose edit the properties for this field. With the customer name field settings open, you can see I can click on the 'Must be unique box.' This box is checked it will require all entries in that field be unique. In this case, because I have existing data I may also want to check existing entries for duplicate values. Now, because I know I just entered a duplicate value, let's see what happens when I check that box and click Save. You'll notice QuickBase has given me an error saying the existing values in the field customer name are not unique. Unfortunately, this is the most information I'm going to get. I'll need to go back into my table and sort by that field and identify those duplicate records. I could also create a summary report with that field in order to find my duplicate records and change them either to no longer be duplicate or to delete the duplicate record. We'll go ahead and click OK and let's go ahead and delete that record ourselves. Back on the record, I can now delete the customer. And here I'll go ahead and make another edit to the customer name field properties getting here slightly different way this time from the report. And now that I know I don't have any more duplicates I can check the 'Must be unique' and 'Check for duplicate entries' and click Save. You'll see here it allowed me to save because there are no duplicate entries. Well, let's see what happens when I try to enter a duplicate customer. You'll see I've gotten this error message that says that "The fields that are marked unique must contain unique values for all records. You have entered a duplicate value for the unique field customer name please check your data and try again. The customer was not saved." So in this instance, we prevented that duplicate customer......"
