A database management system is a software package for creating and managing databases. Many different types of database systems exist based on how they manage the database structure.
Two types of database structure
Databases typically have one of two basic forms:
- single-file or flat file database
- multi-file relational or structured database
A flat file databasestores data in a plain text file, with each line of text typically holding one record. Delimiters such as commas or tabs separate fields. A flat file database uses a simple structure and, unlike a relational database, cannot contain multiple tables and relations.
A relational databasecontains multiple tables of data with rows and columns that relate to each other through special key fields. These databases are more flexible than flat file structures, and provide functionality for reading, creating, updating, and deleting data. Relational databases use Structured Query Language (SQL) - a standard user application that provides an easy programming interface for database interaction.
Types of relationships in a database
Four types of relationships exist in relational database design:
- one to one - where one table record relates to another record in another table
- one to many - where one table record relates to multiple records in another table
- many to one - where more than one table record relates to another table record
- many to many - where multiple records relate to more than one record in another table
These relations form functional dependencies within the database. Some common examples of relational databases include MySQL, Microsoft SQL Server, Oracle, etc.
Four types of database management systems
A relational database management system is one of four common types of systems you can use to manage your business data. The other three include:
- hierarchical database systems
- network database systems
- object-oriented database systems
Ahierarchical database modelresembles a tree structure, similar to a folder architecture in your computer system. The relationships between records are pre-defined in a one to one manner, between 'parent and child' nodes. They require the user to pass a hierarchy in order to access needed data. Due to limitations, such databases may be confined to specific uses.
Network database models also have a hierarchical structure. However, instead of using a single-parent tree hierarchy, this model supports many to many relationships, as child tables can have more than one parent.
Finally, in object-oriented databases, the information is represented as objects, with different types of relationships possible between two or more objects. Such databases use an object-oriented programming language for development.
NoSQL or non-relational databases
A popular alternative to relational databases, NoSQL databases take a variety of forms and allow you to store and manipulate large amounts of unstructured and semi-structured data. Examples include key-value stores, document stores and graph databases.
Which database is right for you?
Businesses with simple database requirements often use standard office tools, such as spreadsheets. However, if you use large amounts of data or have complex business needs, you may need to consider more capable database systems that offer better functionality. Find tips to help you decide which is the best database for your business.