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Database normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It was first proposed by British computer scientist Edgar F. Codd as part of his relational model. Normalization entails organizing the columns ...
The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database. [citation needed] These integrity constraints ensure compatibility between parts of the schema. All constraints are expressible in the same language. A database can be considered a structure in realization of the ...
Database catalog. A database catalog of a database instance consists of metadata in which definitions of database objects such as base tables, views (virtual tables), synonyms, value ranges, indexes, users, and user groups are stored. [1][2] It is an architecture product that documents the database's content and data quality. [3]
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 ...
MySQL (/ ˌmaɪˌɛsˌkjuːˈɛl /) [ 5 ] is an open-source relational database management system (RDBMS). [ 5 ][ 6 ] Its name is a combination of "My", the name of co-founder Michael Widenius 's daughter My, [ 7 ] and "SQL", the initialism for Structured Query Language.
Reserved words in SQL and related products. In SQL:2023 [ 3 ] In IBM Db2 13 [ 4 ] In Mimer SQL 11.0 [ 5 ] In MySQL 8.0 [ 6 ] In Oracle Database 23c [ 7 ] In PostgreSQL 16 [ 1 ] In Microsoft SQL Server 2022 [ 2 ] In Teradata 15 [ 8 ]
Join (SQL) A Venn diagram representing the full join SQL statement between tables A and B. A join clause in the Structured Query Language (SQL) combines columns from one or more tables into a new table. The operation corresponds to a join operation in relational algebra. Informally, a join stitches two tables and puts on the same row records ...
Data definition language. Saving a ddl file in Oracle SQL Developer. In the context of SQL, data definition or data description language (DDL) is a syntax for creating and modifying database objects such as tables, indices, and users. DDL statements are similar to a computer programming language for defining data structures, especially database ...