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Short title: Oracle Database/Print version - Wikibooks, open books for an open world; Author: hbossot: Image title: File change date and time: 04:35, 3 June 2016
A database trigger is like a stored procedure that Oracle Database invokes automatically whenever a specified event occurs. It is a named PL/SQL unit that is stored in the database and can be invoked repeatedly. Unlike a stored procedure, you can enable and disable a trigger, but you cannot explicitly invoke it.
Interactive access to the Oracle Rdb can be by SQL (Structured Query Language), RDO (Relational Database Operator), or both. High level languages usually access Oracle-Rdb by: embedding RDO statements in the source file then running it through a precompiler (example: "file.RCO" is pre-compiled into "file.COB")
In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...
A candidate key, or simply a key, of a relational database is any set of columns that have a unique combination of values in each row, with the additional constraint that removing any column could produce duplicate combinations of values. A candidate key is a minimal superkey, [1] i.e., a superkey that doesn't contain a smaller one. Therefore ...
Database objects are concepts that refer to relational or sequential databases and persist being valid in new models. Tables , triggers , columns , indexes are examples of database objects, [ 7 ] which are present in O-PL/SQL, but with the same meaning of the notion of Java objects, specifically an element of a set that has its existence ...
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 ...
Increasingly, the Oracle database products compete against open-source software relational and non-relational database systems such as PostgreSQL, MongoDB, Couchbase, Neo4j, ArangoDB and others. Oracle acquired Innobase , supplier of the InnoDB codebase to MySQL , in part to compete better against open source alternatives, and acquired Sun ...