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  2. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    An index normally includes a "key" or direct link to the original row of data from which it was copied, to allow the complete row to be retrieved efficiently. Some databases extend the power of indexing by letting developers create indexes on column values that have been transformed by functions or expressions.

  3. XLeratorDB - Wikipedia

    en.wikipedia.org/wiki/XLeratorDB

    In addition, SQL Server uses Transact-SQL (T-SQL) [17] to execute four major classes of pre-defined functions in native mode. [10] Functions operating on the DBMS offer several advantages over client layer applications like Excel: they utilize the most up-to-date data available; they can process far larger quantities of data; and, the data is ...

  4. Data Analysis Expressions - Wikipedia

    en.wikipedia.org/wiki/Data_Analysis_eXpressions

    Data Analysis Expressions (DAX) is the native formula and query language for Microsoft PowerPivot, Power BI Desktop and SQL Server Analysis Services (SSAS) Tabular models. DAX includes some of the functions that are used in Excel formulas with additional functions that are designed to work with relational data and perform dynamic aggregation.

  5. PostgreSQL - Wikipedia

    en.wikipedia.org/wiki/PostgreSQL

    Indexes in PostgreSQL also support the following features: Expression indexes can be created with an index of the result of an expression or function, instead of simply the value of a column. Partial indexes, which only index part of a table, can be created by adding a WHERE clause to the end of the CREATE INDEX statement. This allows a smaller ...

  6. Expression index - Wikipedia

    en.wikipedia.org/wiki/Expression_index

    A common use for an expression index is to support case-insensitive searching or constraints. For example, if a web site wants to make user names case-insensitive, but still preserve the case as originally entered by the user, an index can be created on the lower-case representation of the user name:

  7. PL/SQL - Wikipedia

    en.wikipedia.org/wiki/PL/SQL

    PL/SQL refers to a class as an "Abstract Data Type" (ADT) or "User Defined Type" (UDT), and defines it as an Oracle SQL data-type as opposed to a PL/SQL user-defined type, allowing its use in both the Oracle SQL Engine and the Oracle PL/SQL engine. The constructor and methods of an Abstract Data Type are written in PL/SQL.

  8. User-defined function - Wikipedia

    en.wikipedia.org/wiki/User-defined_function

    A scalar function returns only a single value (or NULL), whereas a table function returns a (relational) table comprising zero or more rows, each row with one or more columns. User-defined functions in SQL are declared using the CREATE FUNCTION statement. For example, a user-defined function that converts Celsius to Fahrenheit (a temperature ...

  9. MultiDimensional eXpressions - Wikipedia

    en.wikipedia.org/wiki/MultiDimensional_eXpressions

    Multidimensional Expressions (MDX) is a query language for online analytical processing (OLAP) using a database management system. Much like SQL, it is a query language for OLAP cubes. [1] It is also a calculation language, with syntax similar to spreadsheet formulae.