🛢DBMS: Unique Index (Definitions)

"Indexes which do not permit any two rows in the specified columns to have the same value. SQL Server checks for duplicate values when you create the index (if data already exists) and each time data is added." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Restricts duplicate values in a column." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An index in which no two rows are permitted to have the same index value, thus prohibiting duplicate index or key values. The system checks for duplicate key values when the index is created and checks each time data is added with an INSERT or UPDATE statement." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An index with perfect selectivity, that is, an index with no duplicate values allowed. Standard SQL allows multiple NULLs in a unique index, since a NULL is not considered to be equal to any other value, including another NULL. Many DBMSs, however, accept only one NULL in a unique index. Some DBMSs won't allow even a single NULL." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A b-tree index whose keys are not duplicated." (Bob Bryla, "Oracle Database Foundations", 2004)

"This is a special index that prevents users from inserting the same value into a column (or columns) more than once." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An index that enforces uniqueness for a particular field across a single collection." (MongoDb, "Glossary", 2008)

"Sometimes created explicitly by the user, and sometimes created automatically by the database server. By guaranteeing one-and-only-one value for a given table, this structure speeds access to information and preserves data integrity." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"An index in which no two rows are permitted to have the same index value, thus prohibiting duplicate index or key values." (Microsoft, "SQL Server 2012 Glossary,", 2012)

"An index that ensures that no identical key values are stored in a column or a set of columns in a table." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: CLR stored procedure (Definitions)

 "A stored procedure that is created by referencing a SQL Server assembly. The implementation of the CLR stored procedure is defined in an assembly that is created in the .NET Framework CLR." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A stored procedure created against a SQL Server assembly whose implementation is defined in an assembly created in the .NET Framework common language runtime (CLR)." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: Table-Valued Functions [TVFs] (Definitions)

"a function that returns a result set because it returns a SELECT statement from a table." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"User-defined function in which a table is returned as a result, as opposed to a single data value." (Sara Morganand & Tobias Thernstrom , MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442, 2007)

"A user-defined function that returns a table." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: System Stored Procedure (Definitions)

"Stored procedures that SQL Server supplies for use in system administration. These procedures are provided as shortcuts for retrieving information from the system tables, or mechanisms for accomplishing database administration and other tasks that involve updating system tables." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A SQL Server-supplied, precompiled collection of Transact-SQL statements. System stored procedures are provided as shortcuts for retrieving information from system tables or as mechanisms for accomplishing database administration and other tasks that involve updating system tables. The names of all system stored procedures begin with sp_. System stored procedures are located in the master database and are owned by the system administrator, but many of them can be run from any database. If a system stored procedure is executed in a database other than master, it operates on the system tables in the database from which it is executed. You can write stored procedures (called user-defined stored procedures), which can be executed from any database." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A set of SQL Server-supplied stored procedures that can be used for actions such as retrieving information from the system catalog or performing administration tasks." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A type of stored procedure that supports all of the administrative tasks required to run a SQL Server system." (SQL Server 2012 Glossary, "Microsoft", 2012)

🛢DBMS: Remote Stored Procedure (Definitions)

 "A collection of SQL statements and optional control-of-flow statements stored under a name on a remote server. Remote stored procedures can be called by clients or by SQL Server." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A stored procedure located on one instance of SQL Server that is executed by a statement on another instance of SQL Server. In SQL Server 2000, remote stored procedures are supported, but distributed queries offer greater functionality." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A stored procedure located on one instance of SQL Server that is executed by a statement on another instance of SQL Server." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: Materialized View (Definitions)

"A view whose rows take up space. When you select from a view, the DBMS can elect to do one of two things: (a) it can get the rows from the original table, convert any derived columns, and pass the results to the application or (b) it can create a temporary table and put the rows from the original table(s) into the temporary table, then select from the temporary copy. The latter case results in a materialized view. Materialization is often necessary when there is no one-to-one correspondence between the original table's rows and the view's rows (because there is a grouping) or when many tables are affected and concurrency would be harmed (because there is a join)." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A view that stores the results of the query the view is based on, in addition to the SQL join statement of the view itself. Materialized views may be refreshed manually (on demand), on a regular basis, or when there is a change in the underlying tables on which that view is based." (Bob Bryla, "Oracle Database Foundations", 2004)

"A physically preconstructed view of data containing data copied into the materialized view. Materialized views can be highly efficient in read-only environments and are often used for replication, distribution and in data warehouses." (Gavin Powell, "Beginning Database Design", 2006)

"A view that physically exists through a number of underlying indexes that have been created on it." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A dynamic table that not only contains the SQL query command to generate the rows but also stores the actual rows. The materialized view is created the first time the query is run and the summary rows are stored in the table. The materialized view rows are automatically updated when the base tables are updated." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management 9th Ed", 2011)

"A view that is actually stored as a separate object in order to optimize performance." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A view in which the query result is cached as a concrete table that may be updated from the original base tables from time to time." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A schema object that stores a query result. All materialized views are either read-only or updatable." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"An optimized database object that contains the results of a query. Materialized views can be considered as a form of caching." (Piethein Strengholt, "Data Management at Scale", 2020)

🛢DBMS: Schemas (Definitions)

"A description of a database generated by the data definition language (DDL) of the database management system (DBMS)." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The structure of a database, which includes the definitions of the objects. The database schema includes the tables, columns, defaults, indexes, and relationships." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"Database schema refers to the names of tables, fields, data types, and primary and foreign keys of a database. Database schema is also known as the database structure." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A group of related database objects assigned to a database user. A schema contains tables, views, indexes, sequences, and SQL code. The schema name can be used to qualify objects that are not owned by the user referencing the objects." (Bob Bryla, "Oracle Database Foundations", 2004)

"In the SQL-92 standard, a collection of database objects that are owned by a single user and form a single namespace. A namespace is a set of objects that cannot have duplicate names" (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A description of data that provides context and structure. There are many types of schemas, including database schemas and XML schemas." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"The design of the physical database that defines the tables in the database that correspond to physical data objects. The physical database schema is often referred to by CDI vendors as their data model." (Jill Dyché & Evan Levy, "Customer Data Integration: Reaching a Single Version of the Truth", 2006)

"A grouping mechanism for objects inside a database. A schema is owned by a user, and various users can be assigned permission to use objects in a schema. In SQL Server 2005 the schema is separated from the object owner and is used as the third part of the four-part naming system for objects, which is server.database.schema.object." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A group of database objects that make up a given namespace. Objects include tables, views, and statements that grant or revoke access to other securable objects. No two objects in any namespace can have the same name." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"In SQL Server 2000, the schema identified the model of the database. For example, the tables, VIEWs, data types, and so on would be identified as the schema. In SQL Server 2005, the term schema is used to identify a collection of database entities within a single namespace. Schemas are the owners of the objects, and one or more users can be the owners of schemas." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A collection of tables that forms a database." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"A conceptual data model that shows all the relationships among the data elements under consideration in a given context; the collection of table definitions in a relational database." (Toby J Teorey, "Database Modeling and Design" 4th Ed, 2010)

"In database design theory, the overall logical design of a database. In a SQL DBMS, a group of tables and supporting elements such as views and indexes." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"(1) The logical or physical definition of data elements, physical characteristics, and relationships. (2) The diagram representing a logical data model." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures 2nd Ed", 2012)

"The names of tables, fields, data types, and primary and foreign keys of a database." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: Clustered Index [CI[ (Definitions)

"An index in which the physical order and the logical (indexed) order is the same. The leaf level of a clustered index represents the data pages themselves." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A clustered index forces the rows in a table to be physically stored in sorted order, using one or more columns from the table to sort the rows. A table may have only one clustered index, such as a dictionary." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An index that the DBMS uses to determine the order of data rows, according to values in one or more columns, called the cluster key. With a strong-clustered index, the data pages are the index's leaves and are thus always in order. With a weak-clustered index, data pages are separate from index leaf pages and the rows need not be 100% in order. The terms weak clustered index and strong-clustered index are not common usage; they appear only in this book." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A clustered index in SQL Server is a type of index in which the logical order of key values determines the actual data rows; thereby the data rows are kept sorted. Using a clustered index causes the actual data rows to move into the leaf level of the index." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"This is an index that physically rearranges the data that is inserted into your tables." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An index whose leaf level is the actual data page of the table." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Microsoft, "SQL Server 2012 Glossary", 2012)

"This is an index that contains a table’s row data in its leaf-level nodes." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide" 3rd Ed, 2012)

"An index that contains a table’s row data in its leaf-level nodes." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed, 2015)

"An index whose sequence of key values closely corresponds to the sequence of rows stored in a table. The degree of correspondence is measured by statistics that are used by the optimizer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Clustered Index [CI] (Definitions)

"An index in which the physical order and the logical (indexed) order is the same. The leaf level of a clustered index represents the data pages themselves." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"An index that the DBMS uses to determine the order of data rows, according to values in one or more columns, called the cluster key. With a strong-clustered index, the data pages are the index's leaves and are thus always in order. With a weak-clustered index, data pages are separate from index leaf pages and the rows need not be 100% in order. The terms weak clustered index and strong-clustered index are not common usage; they appear only in this book." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A clustered index in SQL Server is a type of index in which the logical order of key values determines the actual data rows; thereby the data rows are kept sorted. Using a clustered index causes the actual data rows to move into the leaf level of the index." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"This is an index that physically rearranges the data that is inserted into your tables." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A type of index in which the logical order of key values determines the actual order of the data rows and keeps the data rows sorted. Using a clustered index causes the actual data rows to move into the leaf level of the index." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A SQL Server index where the sorted order is the physical order. A table can have only a single clustered index." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"An index whose leaf level is the actual data page of the table." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"This is an index that contains a table's row data in its leaf-level nodes." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Microsoft, "SQL Server 2012 Glossary", 2012)

"This is an index that contains a table’s row data in its leaf-level nodes." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide" 3rd Ed, 2012)

"An index whose sequence of key values closely corresponds to the sequence of rows stored in a table. The degree of correspondence is measured by statistics that are used by the optimizer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A special type of index used to optimize queries. Tables can have only one clustered index. The data is ordered the same way the index is ordered. It's similar to a dictionary or a phone book. When you find the word or name, you're pointed right at the data." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

🛢DBMS: Non-Clustered Index [NCI] (Definitions)

"An index that stores key values and pointers to data. The leaf level points to data pages rather than containing the data itself." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A nonclustered index does not physically arrange data, but points to the data in a table. The pointers are themselves sorted, making it easy to quickly locate data (search) within a table." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An index with a structure completely separate from the data rows it indexes; normally a B-tree. The lowest rows of a non-clustered index contain the index key values, with each key value pointing to the data rows that contain that key. The data rows are not stored in an order based on the index key, but rather in a heap." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An index in which the logical order of the index is different than the physical, stored order of the rows on disk." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"An index in which the logical order of the index is different than the physical, stored order of the rows on disk. In contrast to clustered indexes, non-clustered indexes are totally separated from the actual data rows, causing an unsorted order of data based on non-clustered keys. Non-clustered indexes differ from the clustered indexes at the leaf level. The leaf level of a non-clustered index contains the key value and the row locator. The row locator is either the physical row address (if there is no clustered index) or the clustered index key value (if a clustered index exists)." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"This is an index that does not physically rearrange the data that is inserted into your tables. This index contains pointers to the data that is stored in the table or clustered index." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An index in which the logical order of the index is different from the physical, stored order of the rows on disk. In contrast to clustered indexes, non-clustered indexes are totally separated from the actual data rows, causing an unsorted order of data based on non-clustered keys. Non-clustered indexes differ from clustered indexes at the leaf level. The leaf level of a non-clustered index contains the key value and the row locator. The row locator is either the physical row address (if there is no clustered index) or the clustered index key value (if a clustered index exists)." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A SQL Server index that is separate from the table." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"An index whose leaf level stores only the columns included in the index (key columns and included columns) and holds pointers to the rows in the actual table." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"A non-clustered index is added to optimize queries. Tables can have multiple non-clustered indexes. A non-clustered index is similar to the index in the back of a book. By finding it in the index, you know specifically where to look in the book for the information." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A non-clustered index is an index that stores the clustering key or row ID to the row data in its leaf nodes, depending on whether the table is a clustered table or a heap." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"An index in which the logical order of the index key values is different than the physical order of the corresponding rows in a table. The index contains row locators that point to the storage location of the table data." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A non-clustered index is an index that stores the clustering key or row ID to the row data in its leaf nodes, depending on whether the table is a clustered table or a heap." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide" 3rd Ed., 2012)

"An index that stores the clustering key or row ID of the row data in its leaf nodes, depending on whether the table is a clustered table or a heap." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed., 2015)

🛢DBMS: Tables (Definitions)

"A collection of rows (records) that have associated columns (fields). The logical equivalent of a database file." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A collection of rows that have associated columns." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"The structure within a database that holds the data. A table is made iup of row and columns." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An object in a database that stores data as a collection of rows and columns." (Microsoft Corporation, "Microsoft SQL Server 7.0 System Administration Training Kit", 1999)

"A two-dimensional object, consisting of rows and columns, used to store data in a relational database. Each table stores information about one of the types of objects modeled by the database." (Microsoft Corporation, "Microsoft SQL Server 2000 System Administration", 2001)

"The basic construct of a relational database that contains rows and columns of related data." (Bob Bryla, "Oracle Database Foundations", 2004)

"A collection of rows holding similar columns of data. The corresponding formal database term is relation." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A two-dimensional storage location of data. Databases within SQL Server 2005 are composed of multiple related tables." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A two-dimensional object, consisting of rows and columns, used to store data in a relational database. Each table stores information about one of the types of objects modeled by the database, such as information about sales orders." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A two-dimensional array of data, consisting of one or more rows representing instances of the thing the table describes and one or more columns each containing a kind of data describing that thing." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"In a relational database, the collection of rows (or records) of a single type (similar to a file)." (Toby J Teorey, ", Database Modeling and Design 4th Ed", 2010)

"A two-dimensional arrangement of data into rows and columns." (Craig S Mullins, "Database Administration", 2012)

"A database object that stores data in records (rows) and fields (columns). The data is usually about a particular category of things, such as employees or orders." (Microsoft, "SQL Server 2012 Glossary", 2012)

"In relational databases and also in Excel, where information is stored. Tables are essentially spreadsheets, or lists, that store database information." (E C Nelson & Stephen L Nelson, "Excel Data Analysis For Dummies ", 2015)

"In a relational database, a database object that consists of a specific number of columns and is used to store an unordered set of rows." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Indexes (Definitions)

"A database object that consists of key values from the data tables, and pointers to the pages that contain those values. Indexes speed up access to data rows." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A set of pointers that are logically ordered by the values of a key. An index is a database object that provides access to data in the rows of a table, based on key values. Indexes provide quick access to data and can enforce uniqueness on the rows in a table. SQL Server supports clustered and nonclustered indexes. In a clustered index, data is stored in the same order as the index; in a nonclustered index, data is stored differently from the index." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A database object that provides fast access to data in the rows of a table, based on key values. Indexes can also enforce uniqueness on the rows in a table. SQL Server supports clustered and nonclustered indexes." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A database object designed to reduce the amount of time it takes to retrieve rows from a table. An index is created based on one or more columns in the table." (Bob Bryla, "Oracle Database Foundations", 2004)

"In a relational database, a database object that provides fast access to data in the rows of a table, based on key values. Indexes can also enforce uniqueness on the rows in a table. SQL Server supports clustered and non-clustered indexes. The primary key/unique constraint automatically causes an index to be built. In full-text searches, a full-text index stores information about significant words and their location within a given column." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A data structure that uses one or more columns to make looking up values on those columns faster." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"In a relational database, a database object that provides fast access to data in the rows of a table, based on key values. The primary key of a table is automatically indexed." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A physical database object used to quickly access data in a database." (Craig S Mullins, "Database Administration", 2012)

🛢DBMS: Aggregate Function (Definitions)

"A function that works on a set of cells to produce a single answer or set of answers, one for each subset of cells. The aggregate functions available in Transact-SQL are: average (avg), maximum (max), minimum (min), sum (sum), and count of the number of items (count)." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Include SUM, AVG, COUNT, COUNT(*), MAX, and MIN. These functions generate summary values that appear as new columns in query results. They act on the whole table or on a subset of the rows." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"Functions that calculate summary values, such as averages and sums, from the values in a particular column and return a single value for each set of rows to which the function applies. The aggregate functions are AVG, COUNT, COUNT(*), MAX, MIN, SUM, STDEV, STDEVP, VAR, and VARP. Aggregate functions can be applied either to all rows in a table, to a subset of table rows specified by a WHERE clause, or to one or more groups of table rows specified by the GROUP BY clause." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An aggregate function performs a calculation on a column in a set of rows and returns a single value." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A type of function in Oracle SQL that performs a calculation or transformation across multiple rows in a table, rather than just on a single row." (Bob Bryla, "Oracle Database Foundations", 2004)

"Functions that provide summary data over sets returning a singular value." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A function that performs a calculation at the column level on a set of rows to return a single value. Examples of T-SQL aggregate functions include AVG, MIN, and SUM." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A function that produces a single result based on the contents of an entire set of table rows." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A function that performs a summary calculation on a series of data and returns a single value. Each aggregate function uses the Scope parameter, which defines the scope (such as grouping, data set, or data region) in which the aggregate function is performed." (Jim Joseph et al, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A SQL function - for example, AVG and SUM - that computes a variety of measures based on values in one or more numeric columns." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"A function that performs a calculation on multiple values and returns a single value." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A function that optionally accepts arguments and returns a single scalar value that is the result of an evaluation of a set of like values, such as those in a column within a set of one or more rows. See also function, routine." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A function that generates a single value from a group of values, often used with GROUP BY and HAVING clauses. Aggregate functions include AVG, COUNT, MAX, MIN, and SUM. Also known as set functions. See also scalar function." (Microsoft, "ODBC Glossary")

"A function that performs a calculation on multiple values and returns a single summary value." (Microsoft Technet)

"In a query, a function such as COUNT, AVG, or STDEV that calculates a value using all the rows in a column of a table. In writing expressions and in programming, you can use SQL aggregate functions (including the three listed above) and domain aggregate functions to determine various statistics." (Microsoft, "ADO Glossary Terms")

🛢DBMS: Function (Definitions)

"A set of instructions that operates as a single logical unit, can be called by name, accepts input parameters, and returns information. In programming languages such as C, a function is a named subroutine of a program that encapsulates some logic. The function can be called by name, using parameters to pass data into the function and retrieve data produced by the function. In Transact-SQL, a function is a unit of syntax consisting of a keyword and, usually, a set of parameters. There are several categories of Transact-SQL functions: string, math, system, niladic, text and image, date, aggregate, and conversion functions." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A program that returns a value to the program or environment from which it is called." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A section of code that operates as a single logical unit. Transact-SQL supports both built-in functions and user-defined functions. The built-in functions cannot be modified by SQL Server 2000 users, whereas users can create and modify user- defined functions." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A named set of predefined programming language commands that performs a specific task given zero, one, or more arguments and returns a value." (Bob Bryla, "Oracle Database Foundations", 2004)

"A programming unit or expression returning a single value, also allowing determinant values to be passed in as parameters. Thus, parameter values can change the outcome or return result of a function. The beauty of a function is that it is self-contained and can thus be embedded into an expression." (Gavin Powell, "Beginning Database Design", 2006)

"A set of instructions that operates as a single logical unit." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A centralized, server-based routine that can be included as part of your Transact-SQL statements. Typically used to streamline logic and reduce the amount of required programming effort, you can build your own functions." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"Functions are routines that can accept parameters, perform an action, and return the result of that action. SQL Server includes many built-in functions. User- defined functions can be created to meet specific needs." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions, including C, Visual Basic, and Transact-SQL. Transact-SQL supplies built-in functions, which cannot be modified, and supports user-defined functions, which can be created and modified by users." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A small program that performs one task and returns a single value. It may be built into the SQL language or written by a user, database administrator, or application programmer." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions." (SQL Server 2012 Glossary, "Microsoft", 2012)

"A predefined algorithm supported by the DBMS for converting, manipulating, or calculating data based upon input. Functions can be used within SQL statements any place an expression can be used." (Craig S Mullins, "Database Administration", 2012)

"A relationship between a set of input data values and a set of result values that is used to extend and customize SQL or XQuery. Functions are invoked from elements of SQL statements such as the select list or the FROM clause and from XQuery as primary expressions." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: User-defined Functions [UDFs] (Definitions)

"A Transact- SQL function defined by a user. Functions encapsulate frequently performed logic in a named entity that can be called by Transact-SQL statements instead of recoding the logic in each statement." (Microsoft Corporation, Microsoft SQL Server 2000 system administration, 2001)

"Functions that you write as opposed to built-in functions supplied by a programming language." (Greg Perry, "Sams Teach Yourself Beginning Programming in 24 Hours" 2nd Ed., 2001)

"A user-defined function is a Transact-SQL function defined by a user. Functions encapsulate frequently performed logic in a named entity that can be called by Transact-SQL statements instead of recoding the logic in each statement." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A function that is written by an analyst, user, or database administrator and does not come as part of the default installation of the Oracle server software." (Bob Bryla, "Oracle Database Foundations", 2004)

"A collection of T-SQL statements with a well-defined set of input parameters, but only one output which can be a scalar value or a table. User-defined functions allow the encapsulation of various logical and database operations, but cannot be used to affect changes to a database." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A custom function written by developers in SQL Server." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance 70-444" , 2007)

"A Transact-SQL function defined by a user. Functions encapsulate frequently performed logic in a named entity that can be called by Transact-SQL statements instead of recoding the logic in each statement." (Microsoft Docs, SQL Server 2005)

"Extensible code added to the DBMS to be callable like built-in database functions." (Craig S Mullins, "Database Administration" 2nd Ed, 2012)

"A function that is defined to the DB2 database system by using the CREATE FUNCTION statement and that can be referenced thereafter in SQL statements." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"In SQL Server, a Transact-SQL function defined by a user." (Microsoft Technet)

"A user-defined routine that returns at least one value. (IBM)