Some Things You May Not Know About Relational Databases
Tue 24th March 2009
What is a relational database?
It was in 1970 that Ted Codd, a researcher at IBM, wrote a paper that outlined the 'relational database model', which was to become the cornerstone of database technology as we know it today. Relational databases have since grown in popularity to become probably the most preferred standard for databases. Other types of databases include the hierarchal model, the network model and the object model.
In their infancy databases were 'flat', meaning that the information was stored in one long text file, called a tab delimited file, whereby each entry was separated by a character, such as vertical bar or a backslash. This form of data storage made it difficult and time-consuming to search for specific information and even more difficult to create reports that contained only certain fields from each record.
On the other hand, a relational database is one that contains multiple tables of data that relate to each other through special key fields. It is, in essence, a collection of relations or tables. The standard fields and records are represented as columns (attributes) and rows (tuples). This allows for easy access to and interpretation of specific information.
Advantages of a relational database
A relational database is easy to understand and program, and is easily adapted or upgraded to suit changing requirements as the need arises.
A relational database has excellent security features. A relational database supports access permissions, which allow the database administrator to implement need-based permissions to access the data in database tables. Relational databases support the concept of users and user rights, thus meeting the security needs of databases. Relations are associated with privileges like create privilege, grant privilege, select, insert and delete privileges, which authorise different users for corresponding operations on the database.
A relational database minimises errors in several ways. There is a single storage location for any set of data, so data updates are simplified as it is not necessary to change the same information in all the applicable files, therefore the data will always be current, without a chance of old data remaining in an overlooked file. All data is validated upon entry to filter implausible values and can be cross-checked against existing information.
Logical structure of the data is separate from the physical data. The logical structure of the data does not depend on a relationship between rows. A query specifies a set of rows based on their attributes. This eliminates the oft-occurring situation where the physical sort order of data determines the results. i.e. you get the same result, regardless of the (sort) order of the rows.
Relational databases and Microsoft Access
Microsoft Access, an entry-level database creation and management solution, is undeniably one of the most flexible and user-friendly options available at present.
Enrol in an Access database course now to learn more about relational databases, the advantages and the set-up and management thereof.
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