History of Database Following the technology progress in the areas of processors , computer memory , computer storage , and computer networks , the sizes, capabilities, and performance of databases and their respective DBMSs have grown in orders of magnitude. The development of database technology can be divided into three eras based on data model or structure: navigational , SQL/ relational , and post-relational. The two main early navigational data models were the hierarchical model , epitomized by IBM's IMS system, and the CODASYL model ( network model ), implemented in a number of products such as IDMS . The relational model , first proposed in 1970 by Edgar F. Codd , departed from this tradition by insisting that applications should search for data by content, rather than by following links. The relational model employs sets of ledger-style tables, each used for a different type of entity. Only in...