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A database object is a structure for storing, managing and presenting application- or user-specific data in a database. Depending on the database management system (DBMS), many different types of database objects can exist. [1] [2] The following is a list of the most common types of database objects found in most relational databases (RDBMS):
A view is defined by giving a name to such an expression, such that the name can subsequently be used as a variable name. (Note that the expression must then mention at least one base relation variable.) By using a Data Definition Language (DDL), it is able to define base relation variables. In SQL, CREATE TABLE syntax is used to define base ...
Many filesystems found on common operating systems, including the NTFS filesystem which is used in modern versions of Microsoft Windows, store files and other objects only as a stream of bytes, and have little or no information about the data stored in the files. Such file systems also provide only a single way of organizing the files, namely ...
The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.
SQL is a well known query language and data manipulation language for relational databases; XQuery is a query language for XML data sources; XPath is a declarative language for navigating XML documents; YQL is an SQL-like query language created by Yahoo! Search engine query languages, e.g., as used by Google [5] or Bing [6]
Relationships provide directed, named, semantically-relevant connections between two node entities. A relationship always has a direction, a start node, an end node, and exactly one relationship type. Like nodes, relationships can also have properties. [4] Labels can group similar nodes together by assigning zero or more node labels.
This list includes SQL reserved words – aka SQL reserved keywords, [1] [2] as the SQL:2023 specifies and some RDBMSs have added. Reserved words in SQL and related products In SQL:2023 [ 3 ]
PostgreSQL schemas are namespaces, allowing objects of the same kind and name to co-exist in a single database. They are not to be confused with a database schema —the abstract, structural, organizational specification which defines how every table's data relates to data within other tables.