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In Relational Database Design, in some cases the existence of one kind of relationship type precludes the existence of another. Entities within an entity type A may be related by a relationship type R to an entity in entity type B or entity type C but not both. The relationship types are said to be mutually exclusive.
Java, C#, C, Python, Go, Node.js, Perl, libevent, PHP, Ruby, Rust Open Source (AGPL) Flash-optimized in-memory open source NoSQL database. ALTIBASE HDB: Altibase Corporation 1999 Java, C, C++, JDBC, ODBC, SQL Proprietary Altibase is a hybrid DBMS that combines an in-memory database with a conventional disk-resident database in a single unified ...
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 Language) for querying and updating the database.
In a simple relational database implementation, each row of a table represents one instance of an entity type, and each field in a table represents an attribute type. In a relational database a relationship between entities is implemented by storing the primary key of one entity as a pointer or "foreign key" in the table of another entity.
Although relational databases are a common persistence layer in software applications, numerous other persistence layers exist. CRUD functionality can for example be implemented with document databases, object databases, XML databases, text files, or binary files.
Most relational databases use the SQL data definition and query language; these systems implement what can be regarded as an engineering approximation to the relational model. 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 ...
The exact and correct implementation of stored procedures varies from one database system to the other. Most major database vendors support them in some form. Depending on the database system, stored procedures can be implemented in a variety of programming languages, for example SQL, Java, C, or C++. Stored procedures written in non-SQL ...
[5] [6] A relational database definition (database schema, sometimes referred to as a relational schema) can thus be thought of as a collection of named relation schemas. [7] [8] In implementations, the domain of each attribute is effectively a data type [9] and a named relation schema is effectively a relation variable (relvar for short).