Relational databases first made an appearance in the mid 1970s, between the years 1974 and 1977 with the creation of Ingres and System R which led to the creation of MS SQL Server, Sybase, Wang’s PACE and Britton-Lee to name a few (Quickbase, n.d.).
It was only until the 1980s that SQL (Structured Query Language) became the standard query language used by relational databases.
Basic features of the relational data model:
- Data is stored only once
The relational model recommends data to only be stored once and for additional times the data may be needed, for it to be queried by means of a JOIN. This makes sure that duplication never occurs and multiple sources never need to be updated.
There is always a single source of truth (Borysowich, 2008).
- Each row is unique
Each row in a table is inserted with a unique key, called the `primary key`. This key is often an automatically incremented number. Data that is stored in separate tables can then be joined together using these primary keys (Jiang, n.d.).
- Each column’s data type is constrained
Each time data is inserted into a table, each column has a constraint type, such as an integer of a maximum certain length, or character count. This is useful to guarantee a telephone number field does not end up containing a name or other incorrect information (Tekstenuitleg.net, n.d.).
- Structured Query Language / SQL
Possibly the most important functionality of a relational database is the standard query language to insert, update, delete and alter information.
All relational databases adhere to one of the slight variations of SQL available (Sirkin, n.d.).
- Portable between RDSs
Data is portable between other relational database systems.
If data is stored in a MySQL database, it is not terribly difficult to move the records to a MS SQL, PostgreSQL or other relational alternative database.
An end user and/or database designer can have a positive experience using a relational database because there are many constructive yet pragmatic features to both querying and designing databases of this nature.
With a pre-laid out use case it is fairly intuitive for a database designer to quickly prototype and start filling a relational database with information. The application developer or end user can then use standardised querying language to operate this database with minimal ease and 100 percent reliability.
Relational databases have been around for tens of years and with continual advancements in hardware systems, it is almost impossible to find a place to not use them in any size organisation.
Quickbase (n.d.) A Timeline of Database History [Online] Quickbase.com, Available from: http://www.quickbase.com/articles/timeline-of-database-history (Accessed on 27th October 2017)
Borysowich, C (2008) Characteristics of Relational Databases [Online] Toolbox.com, Available from: http://it.toolbox.com/blogs/enterprise-solutions/characteristics-of-relational-databases-24134 (Accessed on 27th October 2017)
Jiang, Z (n.d.) Properties of Relational Tables [Online] CS.wcupa.edu, Available from: https://www.cs.wcupa.edu/~zjiang/RDB_table.htm (Accessed on 27th October 2017)
Tekstenuitleg.net (n.d.) Relational database characteristics [Online] Tekstenuitleg.net, Available from: http://en.tekstenuitleg.net/articles/software/database-design-tutorial/database-characteristics.html (Accessed on 27th October 2017)
Sirkin, J (n.d.) SQL (Structured Query Language) [Online] Techtarget.com, Available from: http://searchsqlserver.techtarget.com/definition/SQL (Accessed on 27th October 2017)