Category Archives: Design Principles

Table Types

To my way of thinking, there are two types of tables. Entity Tables and Transaction Tables. It is important to understand the difference. Entity Describes an entity and its attributes. Customers are entities, Products are entities. You can edit an entity’s attributes. I always like to use a Log table that takes a copy of… Read More »

Outer Joins in Access

The Access Query Designer does some great stuff but what it won’t do is an Outer Join. What is an Outer Join? If we have two tables, in this example Sales and Orders and we want to see a full list of customers who have placed Either an Order or a Sale and also see… Read More »

Normalisation

A relational database allows you to ‘normalise’ your data. Normalising data means that you only have to store repeated information in one place. For example, if you are storing invoice data then each invoice for the same Customer does not need to store the address of the customer, this is held in a Customer table… Read More »

Naming Conventions

When Naming Objects, The first purpose of Naming Conventions is to ensure that the names of objects are unique. Access may allow you to give the same name as a table to a form or report (but not a query) but that doesn’t mean you should. At some point you may need to rename an object… Read More »

Requerying Combo and List Boxes

If you add, or edit, records in a Form then any Combo or List box based on that form’s Datasource is no longer up to date. I’ve seen many attempts to handle this and most are very clunky, others difficult to maintain. What we should be doing is requerying all the Lists in our Application when,… Read More »