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In database theory, a conjunctive query is a restricted form of first-order queries using the logical conjunction operator. Many first-order queries can be written as conjunctive queries. In particular, a large part of queries issued on relational databases can be expressed in this way.
A hierarchical database model is a data model in which the data is organized into a tree-like structure. The data are stored as records which is a collection of one or more fields . Each field contains a single value, and the collection of fields in a record defines its type .
Data field label = Employee Name or EMP_NAME Data field value = Jeffrey Tan The above description is a view of data as understood by a user e.g. a person working in Human Resource Department. The above structure can be seen in the hierarchical model, which is one way to organize data in a database. [2] In terms of data storage, data fields are ...
An object database or object-oriented database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented. A third type, object–relational databases, is a hybrid of both approaches. Object ...
Laravel 3 was released in February 2012 with a set of new features including the cmd command-line interface (CLI) named Artisan, built-in support for more database management systems, database migrations as a form of version control for database layouts, support for handling events, and a packaging system called Bundles. An increase of Laravel ...
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).
A variety of difficulties arise when considering how to match an object system to a relational database. These difficulties are referred to as the object–relational impedance mismatch. [4] An alternative to implementing ORM is use of the native procedural languages provided with every major database.
A sort field keeps sibling records in a particular order. Hierarchical structures were widely used in the early mainframe database management systems, such as the Information Management System (IMS) by IBM, and now describe the structure of XML documents. This structure allows one-to-many relationship between two types of data.