Information: - A database abstraction layer is an application programming interface which unifies the communication between a computer application and databases such as SQL Server, DB2, MySQL, PostgreSQL, Oracle or SQLite. Traditionally, all database vendors provide their own interface tailored to their products, which leaves it to the application programmer to implement code for all database interfaces he or she would like to support. Database abstraction layers reduce the amount of work by providing a consistent API to the developer and hide the database specifics behind this interface as much as possible. There exist many abstraction layers with different interfaces in numerous programming languages. If an application has such a layer built in, it is called database-agnostic. - PostgreSQL, often simply Postgres, is an object-relational database (ORDBMS) i.e. a RDBMS, with additional (optional use) "object" features with an emphasis on extensibility and standards compliance. As a database server, its primary function is to store data securely, and to allow for retrieval at the request of other software applications. It can handle workloads ranging from small single-machine applications to large Internet-facing applications (or for data warehousing) with many concurrent users; on macOS Server, PostgreSQL is the default database; and it is also available for Microsoft Windows and Linux (supplied in most distributions). - MySQL (officially pronounced as "My S-Q-L",) is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius' daughter, and "SQL", the abbreviation for Structured Query Language. The MySQL development project has made its source code available under the terms of the GNU General Public License, as well as under a variety of proprietary agreements. MySQL was owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now owned by Oracle Corporation. For proprietary use, several paid editions are available, and offer additional functionality. - SQL (or , Structured Query Language) is a special-purpose domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). - SQLite (or ) is a relational database management system contained in a C programming library. In contrast to many other database management systems, SQLite is not a clientserver database engine. Rather, it is embedded into the end program. - The Doctrine Project ( or Doctrine ) is a set of PHP libraries primarily focused on providing persistence services and related functionality . Its prize projects are an object - relational mapper ( ORM ) and the database abstraction layer it is built on top of . One of Doctrine 's key features is the option to write database queries in a proprietary object oriented SQL dialect called Doctrine Query Language ( DQL ) . - A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. The data are typically organized to model aspects of reality in a way that supports processes requiring information, such as modelling the availability of rooms in hotels in a way that supports finding a hotel with vacancies. What object entity has the relation of 'instance of' with the subject 'doctrine '? Choices: - abstraction - api - application - combination - company - corporation - data - database - database abstraction layer - database management system - engine - function - information - interface - internet - language - library - license - name - object - profit - project - query language - single - system
Answer:
library