One of the first steps towards computing, and more specifically data storage was with the Jacquard loom, invented in 1801 by Joseph Marie Jacquard, a loom that used punch cards in order to store patterns. While the loom did not do any computations, it was the first to used punch cards a way to control a series of operations. This is considered an important step in computing, and inspired the first general-purpose computers, Charles Babbage’s Analytical engine. From then on, the punch card was used as the first storage medium for computers, and would influence the first DBMS.
Navigational/Hierarchical
Because of the way that data was stored, first with punch cards, paper tape (like a punch card, but a long strip of paper with holes like punch cards), and magnetic tapes, all data was stored and read sequentially, there was no random access. This physical limitation of the storage medium is reflected in the first type of DBMS, the Navigational DBMS, first created in the 60s. In this type of database, the looking for data is done by navigating through a series of pointers until the needed data was found. In this type of database, queries that are taken for granted today, such as returning all the entries with a specific characteristic would require the DBMS read all the entries one by one and return the data which had the characteristic, there were no searches, as that operation would have been too costly for the support.
Relational
With the advent of hard drives as a suitable storage device, the limitations of sequential reading were removed and DBMS were able to evolve into relational DBMS, which are still being used today. Relational DBMS were designed by Edgar Codd, who at the time was working at IBM, in the offices primarily involved in the development of hard drives. Relational DBMS are designed on a branch of mathematics called tuple calculus. In relational DBMS, data is stored in separate tables, storing different types of related data. In each table, every entry must be unique, with one value, called a primary key indentifies a table’s entry. Tables are linked together by inserting one table’s primary key into an other table. This key becomes in second table (the one where the key is inserted) a secondary key, or foreign key. This sort of database allowed for more efficient storage, eliminating some redundencies, and allowd for more efficient searches, for either single elements or sets of data.
The final type of DBMS is still a relational database; however it includes adds a standardized query language or SQL. This standardized the end user’s interaction with the different databases. Before this each different vendor had their own way of querying their databases.
Sources/further reading:
http://en.wikipedia.org/wiki/Database_management_system
http://www.mountainman.com.au/software/history/intro.html
http://www.comphist.org/computing_history/new_page_9.htm
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