In the 1960s, corporate computer databases were tangled digital mazes. If a company changed its hard drives or reorganized its filing system, every single computer program in the company broke because software was hard-coded to the exact physical storage addresses on magnetic tapes.
IBM computer scientist Edgar Codd introduced a brilliant separation: the Relational Model. Instead of navigating physical pointers, data is organized into clean, interlocking tables of rows and columns, allowing users to query data in simple logical English without worrying about how disks are arranged.
Codd’s paper gave birth to SQL and modern database infrastructure. By powering global banking ledgers, by organizing inventory for airline reservations, and by enabling corporate enterprise software worldwide, relational databases built the modern data economy.
A relational model of data for large shared data banks
Future users of large data banks must be protected from having to know how the data is organized in the machine (the internal representation). A prompting service which supplies such information is not a satisfactory solution. Activities of users at terminals and most application programs should remain unaffected when the internal representation of data is changed and even when some aspects of the external representation are changed. Changes in data representation will often be needed as a result of changes in query, update, and report traffic and natural growth in the types of stored information. Existing noninferential, formatted data systems provide users with tree-structured files or slightly more general network models of the data. In Section 1, inadequacies of these models are discussed. A model based on n -ary relations, a normal form for data base relations, and the concept of a universal data sublanguage are introduced. In Section 2, certain operations on relations (other than logical inference) are discussed and applied to the problems of redundancy and consistency in the user's model.
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