In the previous section, we learned how tables allow us to create the framework for storing information in a database. Obviously, a database that only stored information would be useless -- we need methods to retrieve information as well. If you simply want to recall the information stored in a table, Microsoft Access allows you to open the table and scroll through the records contained within it. However, the real power of a database lies in its capabilities to answer more complex requests, or queries. Access queries provide the capability to combine data from multiple tables and place specific conditions on the data retrieved.
Let's look again to the Northwind database for an example. Imagine that your organization requires a simple method to create a list of those products that are currently selling above their average price. If you simply retrieved the product information table, fulfilling this task would require a large amount of sorting through data and performing calculations by hand. However, the power of a query allows you to simply request that Access only return those records that meet the above average pricing condition. Additionally, you can instruct the database to only list the name and unit price of the item. Sample output is shown below:
So far, you've learned the concepts behind organizing the information in a database and retrieving information from a database. We still need mechanisms to place information into the tables in the first place! Microsoft Access provides two primary mechanisms to achieve this goal. The first method is to simply bring up the table in a window by double-clicking on it and adding information to the bottom of it, just as one would add information to a spreadsheet.
Access also provides a user-friendly forms interface that allows users to enter information in a graphical form and have that information transparently passed to the database. The figure below provides an example of the form method of data entry. This method is less intimidating for the data entry operator but requires a little more work on the part of the database administrator. Future tutorials on this site will deal with the creation of Microsoft Access forms.