Search results
Results from the Health.Zone Content Network
A relational database ( RDB [1]) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. [2] A database management system used to maintain relational databases is a relational database management system ( RDBMS ). Many relational database systems are equipped with the option of using SQL (Structured Query ...
History. E. F. Codd mentioned nulls as a method of representing missing data in the relational model in a 1975 paper in the FDT Bulletin of ACM-SIGMOD.Codd's paper that is most commonly cited in relation with the semantics of Null (as adopted in SQL) is his 1979 paper in the ACM Transactions on Database Systems, in which he also introduced his Relational Model/Tasmania, although much of the ...
Relation (database) Relation, tuple, and attribute represented as table, row, and column respectively. In database theory, a relation, as originally defined by E. F. Codd, [1] is a set of tuples (d 1 ,d 2 ,...,d n ), where each element d j is a member of D j, a data domain. Codd's original definition notwithstanding, and contrary to the usual ...
The relational model ( RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, [1] [2] where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a ...
Partition (database) Partitioning options on a table in MySQL in the environment of the Adminer tool. A partition is a division of a logical database or its constituent elements into distinct independent parts. Database partitioning is normally done for manageability, performance or availability [1] reasons, or for load balancing.
In the field of databases in computer science, a transaction log (also transaction journal, database log, binary log or audit trail) is a history of actions executed by a database management system used to guarantee ACID properties over crashes or hardware failures. Physically, a log is a file listing changes to the database, stored in a stable ...
Relational algebra. In database theory, relational algebra is a theory that uses algebraic structures for modeling data, and defining queries on it with a well founded semantics. The theory was introduced by Edgar F. Codd . The main application of relational algebra is to provide a theoretical foundation for relational databases, particularly ...
An object–relational database ( ORD ), or object–relational database management system ( ORDBMS ), is a database management system (DBMS) similar to a relational database, but with an object-oriented database model: objects, classes and inheritance are directly supported in database schemas and in the query language.