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An example of such a language is SQL, though it is one that Codd regarded as seriously flawed. [2] The objectives of normalization beyond 1NF (first normal form) were stated by Codd as: To free the collection of relations from undesirable insertion, update and deletion dependencies.
"Nested Tables (Analysis Services - Data Mining)". Microsoft. May 7, 2018. "PL/SQL Collections and Records: Nested Tables". Oracle Database Online Documentation Library, 12c Release 1 (12.1.0.2). 2017. "Oracle Collections: A Definition in Plain English Part 2". Archived from the original on July 1, 2006. "Oracle Database 10g: SQL (Oracle Press)".
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.
An inner join (or join) requires each row in the two joined tables to have matching column values, and is a commonly used join operation in applications but should not be assumed to be the best choice in all situations. Inner join creates a new result table by combining column values of two tables (A and B) based upon the join-predicate.
In computing, online analytical processing, or OLAP (/ ˈ oʊ l æ p /), is an approach to quickly answer multi-dimensional analytical (MDA) queries. [1] The term OLAP was created as a slight modification of the traditional database term online transaction processing (OLTP). [2]
Note (1): Server provides tempdb, which can be used for public and private (for the session) temp tables. [84] Note (2): Materialized views are not supported in Informix; the term is used in IBM's documentation to refer to a temporary table created to run the view's query when it is too complex, but one cannot for example define the way it is ...
A table in a SQL database schema corresponds to a predicate variable; the contents of a table to a relation; key constraints, other constraints, and SQL queries correspond to predicates. However, SQL databases deviate from the relational model in many details, and Codd fiercely argued against deviations that compromise the original principles. [3]