We’ve already looked at databases. However, you might be interested to know a little more about the two most common types of databases, relational and non-relational.
Relational Databases
A relational database works by having groups of data, called tables, that can be related to another table, or tables.
For example, you might have three tables: customers, products, and purchases. Customers and products aren’t related to one another, but purchases relates to customers because you can find out who was buying. Likewise, products are related to the purchase table because it specifies what was bought.
Depending upon the type of data needed to be stored, you could have as few as one table, two tables related to one another, or even up to hundreds of tables in your database.
Most modern databases are relational databases and use the Structured Query Language (SQL) to access and change the data stored within the database.
Common relational databases include the desktop Microsoft Access, MySQL, SQL Server, and Oracle. Of course there are many others as well.
Non Relational Databases
Originally most databases were non-relational. The data was all stored in just a few large complex tables, with no way to relate two or more tables. This is because setting up relationships can take a lot of computer time. As computers got more powerful, most databases became relational.
However, in the last few years, there has been a big push to return to non-relational databases. These databases are often referred to as NoSQL databases because they don’t use SQL, instead they have their own way of producing the CRUD ability for the database.
The reason for this return to non-relational databases is the size and amount of data they can hold. Larger and more complex systems need more data, and sometimes that means that the database spans multiple computers. Trying to relate tables across multiple computers can take too much time to return the answer to a query.
Additionally, if data needs to be replicated on different machines at different locations, let’s say offices in San Fransisco, New York, London, and Melbourne Australia, then a traditional relational database would start to experience problems. However, a NoSQL database would not have those same issues.
Common non-relational databases include Couch DB, MongoDB, as well as many others.
Relational vs Non-Relational Databases was originally found on Access 2 Learn
