Required, unique, and linked fields
Solution No. 670
Required fields
Unique fields
Linked fields
Required fields
Let’s say you have a table that holds customer records. A required field is the field that must be filled out in order for the record to save to the table. While the specific fields may vary from table to table, any table can impose rules of this kind. For example, a customer table might require the Customer Name field to have a value in it in order for the record to save. This makes logical sense because what would be the point in saving a customer with no name?
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Unique fields
A unique field, on the other hand, refers to the value itself. Basically, a unique field is one whose value is different than any other value currently saved in that table. An example would be helpful here, so think about it this way: let’s say you had a table called Colors, consisting of a single field called Name. The point of this table was to save a bunch of colors a customer could choose from. In this case, the Name field would have to be Unique in order for the record to be saved, because there would be no reason for you to have several records for the color “Red”. If this field was set to Unique, trying to save a second record with “Red” in the Name field wouldn’t be allowed.
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Linked fields
Okay, here’s where things get a little more complicated. A linked field is a field that has a relationship with a field in another table. That sounds confusing, so let’s use another example to illustrate what we mean.
Remember when we talked about drop down field types? A drop down field is a great example of how linked fields work, because they create relationships by “pointing” to different tables.
Let’s say for example you are working in the Invoice table. That table has a drop down field called “customer name”, which – as you might expect – provides a list of existing customers to choose from, so you can relate the invoice to that customer’s account. It makes sense that this list is pulling the names from somewhere, but where? Well, basically, the drop down field asks Method for a unique piece of information to populate the field (the most unique field in Method is the record ID field, because as we mentioned earlier, that number can never be duplicated in a table). In this case, it stands to reason that the drop down field would reference the Customer table to populate a list of customer names. Retrieving that information sets up a “road” or “path” between the Invoice and Customer tables.
This opens the door for all sorts of great options by way of a linked field. You can add a linked field to the invoice table that can then link to any table it already has a relationship with (in this case, the customer table). Have you ever seen a screen that automatically fills out an address and phone number when you choose a customer name? That magic comes courtesy of linked fields – once the relationship between two tables is set up, these fields will be populated with the most recent information available in the corresponding record.
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Created on | Aug-21-2015 |
Last modified on | Sep-17-2015 |