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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 ...
Comparison of database administration tools. The following tables compare general and technical information for a number of available database administration tools. Please see individual product articles for further information. This article is neither all-inclusive nor necessarily up to date. Systems listed on a light purple background are no ...
Type. Database management. License. GNU General Public License 2. Website. www.phpmyadmin.net. phpMyAdmin is a free and open source administration tool for MySQL and MariaDB. As a portable web application written primarily in PHP, it has become one of the most popular MySQL administration tools, especially for web hosting services.
InnoDB is a storage engine for the database management system MySQL and MariaDB. [1] Since the release of MySQL 5.5.5 in 2010, it replaced MyISAM as MySQL's default table type. [2] [3] It provides the standard ACID-compliant transaction features, along with foreign key support (declarative referential integrity).
PostgreSQL supports a binary communication protocol that allows applications to connect to the database server. The protocol is versioned (currently 3.0, as of PostgreSQL 7.4) and has a detailed specification. [48] The official client implementation of this communication protocol is a C API, libpq. [49]
Definition: Referential integrity is a database concept that ensures that relationships between tables remain consistent. When one table has a foreign key to another table, the concept of referential integrity states that you may not add a record to the table that contains the foreign key unless there is a corresponding record in the linked table.
A surrogate key (or synthetic key, pseudokey, entity identifier, factless key, or technical key[citation needed]) in a database is a unique identifier for either an entity in the modeled world or an object in the database. The surrogate key is not derived from application data, unlike a natural (or business) key. [1]
Weak entity. In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key. The foreign key is typically a primary key of an entity it is related to. The foreign key is an attribute of the ...