Progress
Database Design
Guide
Computerized Databases
Let’s take a closer look at the example of the filing cabinet database. When a customer calls you to place an order, you go through a series of steps. First, you pull out the customer’s file from the customer cabinet to determine whether the customer is a current account. Then you rummage through the inventory cabinet and pull out the appropriate item files to see whether you have the ordered items in stock. After that, you fill out an order form by listing each item, its price, and the grand total for the order. Finally, you make appropriate changes to the item files in inventory to reflect the current quantity.
Imagine how tedious and unmanageable these repetitive tasks can become if you have several hundred customers calling you each day. In this situation, automating your database makes a lot of sense. A computerized database offers you many advantages, including:
- Centralized and shared data — You enter and store all your data in the computer. This minimizes the use of paper, files, folders, as well as the likelihood of losing or misplacing them. Once the data is in the computer, many users can access it via a computer network. The users’ physical or geographical locations are no longer a constraint.
- Current data — Since users can quickly update data, the data available is current and ready to use.
- Speed and productivity — You can search, sort, retrieve, make changes, and print your data, as well as tally up the totals more quickly than performing these tasks by hand.
- Accuracy and consistency — You can design your database to validate data entry, thus ensuring that it is consistent and valid. For example, if a user enters OD instead of OH for Ohio, your database can display an error message. It can also ensure that the user is unable to delete a customer record that has an outstanding order.
- Analysis — Databases can store, track, and process large volumes of data from diverse sources. You can use the data collected from varied sources to track the performance of an area of business for analysis or to reveal business trends. For example, a clothes retailer can track faulty suppliers, customers’ credit ratings, and returns of defective clothing. An auto manufacturer can track assembly-line operation costs, product reliability, and worker productivity.
- Security — You can protect your database by establishing a list of authorized user identifications and passwords. The security ensures that the user can perform only the operations that you permit. For example, you may allow the user to read data in your database but not allow them to update or delete it.
- Crash recovery — System failures are inevitable. With a database, data integrity is assured in the event of a failure. The database management system uses a transaction log to ensure that your data will be properly recovered when you restart after a crash.
- Transactions — The transaction concept provides a generalized error recovery mechanism to deal with the consequences of unexpected errors. Transactions ensure that a group of related database changes always occur as a unit; either all the changes are made or none of the changes are made. This allows you to restore the previous state of the database should an error occur after you have begun making changes.
Now that you understand the benefits of a computerized database system, let’s take a look at the elements of relational databases.
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