🛢DBMS: Permissions (Definitions)

"A permission is a right to do something in a database. Examples include performing a database function (such as creating table) or working with an object (INSERT)." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

[statement permissions:] "These are database permissions and enable users to create objects, drop objects, or modify objects in a database. Statement permissions do not work with data, but rather work with the containers that hold the data." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"Authorization that enforces database security. SQL Server permissions specify the Transact-SQL statements, views, and stored procedures each user is authorized to use. The ability to assign permissions is determined by each user's status. There are two types of permissions: object permissions and statement permissions." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[statement permission:] "Permission that controls the execution of Transact-SQL statements that create database objects or perform certain administrative tasks. Can be granted, revoked, or denied." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"These are permissions that regulate a user’s ability to create structures that hold data, such as tables and views." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A privilege that you grant to a principle. When authorized, the principle may then interact with one or more securables." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"Operations that can be applied to or done with an object. Example file permissions are read, write, and delete." (Mark Rhodes-Ousley, "Information Security: The Complete Reference", 2nd Ed., 2013)

"Permissions placed on objects within a database. Database permissions specify which actions a database user can perform on tables, views, stored procedures, and other objects." (Mark Rhodes-Ousley, "Information Security: The Complete Reference" 2nd Ed., 2013)

"The definitions of what object access actions are permitted for a specific user or group." (Weiss, "Auditing IT Infrastructures for Compliance" 2nd Ed, 2015)

"The type of authorized interactions that a subject can have with an object. Examples include read, write, execute, add, modify, and delete." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed, 2018)

🛢DBMS: Atomicity (Definitions)

"One of the ACID properties; all or none of the transaction must occur. If all parts of the transaction cannot occur successfully, all effects of the transaction must be undone or 'rolled back'." (Atul Apte, "Java Connector Architecture: Building Custom Connectors and Adapters", 2002)

"Atomicity is a feature provided by transactions. It is a principle that states either all of the transactions’ data modifications are performed or none of them are performed." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

[atomic transaction:] "A possibly complex series of actions that is considered as a single operation by those not involved directly in performing the transaction." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"The requirement that tasks within a transaction occur as a group as if they were a single complex task. The tasks are either all performed or none of them are performed. It's all or nothing." (Rod Stephens, "Beginning Database Design Solutions", 2008)

[atomic unit of work:] "A general category of work that an activity might perform. This kind of activity encapsulates the logic to perform a unit of work synchronously on the workflow thread. The unit of work that is performed is atomic in the sense that it is completed entirely during a single execution of the activity. It doesn’t need to suspend execution and wait for external input. It is short-lived and doesn’t perform time-consuming operations. It executes synchronously on the workflow thread and doesn’t create or use other threads." (Bruce Bukovics, "Pro WF: Windows Workflow in .NET 4", 2010)

"Atomicity is the state or fact of being composed of individual units (NOAD). With regard to data, atomicity refers to what constitutes a unit. In modeling, as data is normalized, each attribute is expected to represent one thing, not a set of things. One system may define a name as one thing. Another may define it as three things (first name, middle initial, last name). Atomicity results from decisions about how to structure data." (Laura Sebastian-Coleman, "Measuring Data Quality for Ongoing Improvement", 2012)

"The characteristic of a transaction whereby database modifications must adhere to an 'all or nothing' rule. If any single part of a transaction fails, the entire transaction fails. A database management system (DBMS) must maintain atomicity despite software and hardware failures (the A in ACID)." (Craig S Mullins, "Database Administration", 2012)

"An attribute or property of a transaction whereby a group of statements are run as if a single operation or none of the statements are run." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Privilege (Definitions)

 "A security attribute that does not have the property of uniqueness and that may be shared by many principals." (Kim Haase et al, "The J2EE™ Tutorial", 2002)

"The right to perform a specific action in the database, granted by the DBA or other database users." (Bob Bryla, "Oracle Database Foundations", 2004)

"A combination of specified resource and actions permitted on the resource." (MongoDb, "Glossary", 2008)

"An action or capability, such as table access, that can be granted to users of the DBMS." (Craig S Mullins, "Database Administration", 2012

"A process that can be performed on a system, such as shut it down, or log in to it remotely." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition, 2nd Ed.", 2013)

"The capability of performing a specific function, sometimes on a specific object. See also authority level, authorization." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Redundancy (Definitions)

"A general term that refers to the capability of an organization to recover from critical database. Redundancy generally involves having more than one source for data, which could be as simple as a backup." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A system that has been set up so that failure at one point does not cause failure of the entire system." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"Storing more than one occurrence of the data." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"the practice of storing more than one occurrence of data. In the case where data can be updated, redundancy poses serious problems. In the case where data is not updated, redundancy is often a valuable and necessary design technique." (William H Inmon, "Building the Data Warehouse", 2005)

"The storage of multiple copies of identical instances of a thing (database, table, record, or value)." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"Here, the provision of information beyond necessity." (Martin J Eppler, "Managing Information Quality" 2nd Ed., 2006)

"The storage of multiple copies of logically identical data. Physically, the data may or may not be identical across systems, and it is not known which is most current or accurate." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The assurance of availability by providing duplicate systems or alternative processes." (Mark Rhodes-Ousley, "Information Security: The Complete Reference" 2nd Ed., 2013)

"Surplus capability, which is maintained to improve the reliability of a system." (Manish Agrawal, "Information Security and IT Risk Management", 2014)

"Process of providing alternative resources in order to continue the execution despite any component failures." (Hamid R Arabnia et al, "Application of Big Data for National Security", 2015)

"Multiple occurrence of the same information in different places." (IQBBA, "Standard glossary of terms used in Software Engineering", 2011)

🛢DBMS: Federated Database (Definitions)

"A database that is spread across multiple servers, often in multiple geographical locations, is called a federated database. The servers that hold the different parts of a federated database are referred to as a federation, or federated database servers. A federation of database servers is used to spread the processing load across a group of servers. The data is horizontally partitioned allowing each of the servers to be independently managed, but distributed queries can be used to process requests on the entire database." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A database system wherein constituent databases, that are geographically decentralized and using various computer systems, are interconnected via a computer network or software that allows metasearching via a single platform. Since the constituent database systems remain autonomous, a federated database system is a contrastable alternative to the task of merging together several disparate databases." (Mila M. Ramos et al, "The CGIAR Virtual Library Bridging the Gap Between Agricultural Research and Worldwide Users", 2009)

"A set of databases that are documented and then interconnected to operate as one database, even when those databases are on different platforms." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

[federated data warehouse:] "1.A conceptual Data Warehouse made up of multiple decision support databases, potentially on multiple servers, but presented transparently to Business Intelligence users as a unified schema for query, analysis, and reporting. 2.An Enterprise Data Warehouse fed by extracts from departmental Data Warehouses and/or legacy Data Warehouses prior to their incorporation and/or retirement." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A distributed database management system (DBMS) that consists of a DB2 instance that operates as a server, a database that serves as the federated database, one or more data sources, and clients (users and applications) who access the database and data sources. A federated system can be used to query and manipulate data that is located on other data servers." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"In a federated system, the database that is within the federated server. Users and applications interface with the federated database. To these clients, the data sources and the federated database seem to be a single database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A set of linked servers that shares the processing load of data by hosting partitions of a distributed partitioned view." (Microsoft Technet)

"A system in which multiple databases appear to function as a single entity. However, the databases typically involved in this kind of system exists independently of the others. Once the different databases are 'combined', one federated database is formed." (Solutions Review)

🛢DBMS: XQuery (Definitions)

"This is a standard method of querying XML data using XML query expressions." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Designed to interrogate XML-based data, this standards-based query language also has some programming capabilities." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"XQuery, or XML Query Language, is an XML query language designed to retrieve and interpret data from diverse XML sources." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"Designed to interrogate XML-based data, this standards-based query language also has some programming capabilities. See also XML." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"A query language for XML. XQuery allows you to query data from XML documents or any data source that can be viewed as XML, such as relational databases. With XQuery, you can query almost any data source as though it were XML, regardless of how the data is physically stored." (John Goodson & Robert A Steward, "The Data Access Handbook", 2009)

"A query language for retrieving data from an XML document or XML database." (Craig S Mullins, "Database Administration", 2012)

"Functional query language that is broadly applicable to a variety of XML data types derived from Quilt, XPath, and XQL." (SQL Server 2012 Glossary, "Microsoft", 2012)

"XML Query Language, an XML query language designed to retrieve and interpret data from diverse XML sources." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

🛢DBMS: Authentication (Definitions)

"In computer security, the process of determining who the user claims to be and whether that claim is correct." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"The step of determining the identity of the requesting client. Single-factor authentication usually is based on a simple password and is the least secure authentication scheme. Two-factor authentication may involve What-You-Know (a password) with What-You-Possess (a plastic card) and is secure enough for banks’ automated teller machines." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"A process that occurs as users attempt to log on to SQL Server 2000. This process verifies that the users are permitted to log on by checking their identity against a database of security accounts. There are two methods of authentication in SQL Server 2000 - Mixed Mode authentication and Windows Authentication. Windows Authentication is recommended for all cases where all SQL Server 2000 users have the ability to log on initially in a Windows environment." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A challenge/response mechanism that ensures that a user connecting to SQL Server is authorized to do so." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"Verification of the user identity." (MongoDb, "Glossary", 2008)

"The process of validating that the user attempting to connect to Reporting Server is authorized to do so." (Jim Joseph et al, "Microsoft® SQL Server™ 2008 Reporting Services Unleashed", 2009)

"The process through which a DBMS verifies that only registered users are able to access the database." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"The process of confirming a user’s or computer’s identity." (Craig S Mullins, "Database Administration", 2012)

"The process of verifying the identity of a user, computer, process, or other entity by validating the credentials provided by the entity. Common forms of credentials are digital signatures, smart cards, biometric data, and a combination of user names and passwords." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The process by which a system verifies a user's identity. User authentication is completed by a security facility outside the DB2 database system, often part of the operating system or a separate product." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"The process by which a user presents credentials to the database, which verifies the credentials and allows access to the database." (Oracle)

🛢DBMS: Data Control Language [DCL] (Definitions)

"The subset of SQL statements used to control permissions on database objects. Permissions are controlled using the GRANT and REVOKE statements." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The subset of SQL statements used to control permissions on database objects. Permissions are controlled using the GRANT and REVOKE statements. See data definition language (DDL) and data manipulation language (DML)." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"A subset of Transact-SQL statements. DCL is used to control permissions on database objects." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A subset of Structured Query Language used to define data security, user function permissions, and data access to data in relational tables." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"SQL statements used for controlling access to data and data structures, e.g., GRANT and REVOKE." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed, 2012)

"The subset of SQL statements used to control permissions on database objects." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: Data Definition Language [DDL] (Definitions)

"The subset of SQL statements used for modeling the structure (rather than the contents) of a database or a cube. The DDL gives you the ability to create, modify, and remove databases and database objects." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Includes statements such as CREATE, ALTER, and DROP to work with objects such as tables. DDL modifies the structure of the objects in a database instead of the contents of the objects." (Bob Bryla, "Oracle Database Foundations", 2004)

"A language, usually part of a database management system, that is used to define all attributes and properties of a database, especially row layouts, column definitions, key columns (and sometimes keying methodology), file locations, and storage strategy." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Commands supported by a database that enable the creation, removal, or modification of structures (such as relational tables or classes) within it." (Pramod J Sadalage & Scott W Ambler, "Refactoring Databases: Evolutionary Database Design", 2006)

"Commands used to change metadata. In some databases, these commands require a COMMIT command; in other database engines, this is not the case. When a COMMIT command is not required, these commands automatically commit any pending changes to the database, and cannot be rolled back." (Gavin Powell, "Beginning Database Design", 2006)

"A component of structured query language (SQL) used to create and delete databases and database objects such as tables and indexes." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"The language component of a DBMS that is used to describe the logical structure of a database." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"The SQL commands that deal with creating the database's structure such as CREATE TABLE, CREATE INDEX, and DROP TABLE." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A special-purpose computer language used to define the schema of a navigational database." (Jan L Harrington, "Relational Database Design and Implementation, 3rd Ed.", 2009)

"1.Generally, the subset of Structured Query Language commands used to define and implement structured database objects. 2.In Database Management Systems, the specific definitions to formally define and implement a database." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The language that allows a database administrator to define the database structure, schema, and subschema." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A language that defines all attributes and properties of a database, especially record layouts, field definitions, key fields, file locations, and storage strategy." Microsoft, "SQL Server 2012 Glossary", 2012)

"SQL statements used for creating and modifying data structures, e.g., CREATE, ALTER, and DROP." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed. , 2012)

"SQL statements used for creating and modifying data structures, e.g., CREATE, ALTER, and DROP." (Craig S Mullins, "Database Administration", 2012)

"A language for describing data and its relationships in a database. See also Data Manipulation Language, relational database management system." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Extent (Definitions)

"Whenever a table or index requires space, SQL Server allocates a block of 8 2K pages, called an extent, to the object." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Eight contiguous pages in SQL. Pages are grouped by eights into extents. Extents are used to allocate space for indexes and tables." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"The space allocated upon creation of a SQL Server object, such as a table or index. In SQL Server, an extent is eight contiguous pages." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A group of pages that are allocated together, as part of the initial creation of an object or when an existing extent becomes full." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"The unit of space allocated to a SQL Server object, such as a table or index, whenever the object needs more space. In SQL Server 2000, an extent is eight contiguous pages." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A contiguous group of blocks allocated for use as part of a table, index, and so forth." (Bob Bryla, "Oracle Database Foundations", 2004)

"The basic unit by which space is allocated to a table or an index. An extent is eight continuous disk pages, which equates to 64 KB." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"This is a group of eight data pages totaling 64KB in size." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A collection of eight contiguous pages used internally by the storage engine in SQL Server 2005 to track the allocation of file space to table and indexes." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"An extent is SQL Server's basic allocation unit of storage. An extent is 64 KB in size and consists of eight logically contiguous data pages, each page being 8 KB in size." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"On a disk or other direct-access storage device, a continuous block of storage space reserved by the operating system for a particular file or program." (Microsoft, "SQL Server 2012 Glossary", 2012)

"SQL Server’s basic allocation unit of storage. An extent is 64 KB in size and consists of eight logically contiguous data pages, each of which is 8 KB in size." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

"An allocation of space, within a container of a table space, to a single database object. This allocation consists of multiple pages." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Equijoin (Definitions)

"A join based on equality." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A join in which the values in the columns being joined are compared for equality, and all columns are included in the results." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A join using the equals operator in the join expression." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A join between two tables where rows are returned if one or more columns in common between the two tables are equal and not NULL." (Bob Bryla, "Oracle Database Foundations", 2004)

"A join operator where the join condition involves equality." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A join based on matching identical values." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"A join that combines two tables based on matching (equivalent) data in rows in the two tables." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A join operator that links tables based on an equality condition that compares specified columns of the tables." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A join in which the values in the columns being joined are compared for equality, and all columns are included in the results." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A join whose join condition contains an equality operator." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"A join whose join condition uses only the equals predicate." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Structured Query Language (Definitions)

"A database query and programming language, commonly pronounced 'sequel'. SQL Server supports an ANSI-standard SQL definition for all computer systems, in addition to T-SQL (Transact-SQL), SQL's own version of the SQL language." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A database query and programming language originally developed by IBM for mainframe computers. It is widely used for accessing data and for querying, updating, and managing relational database systems. There is now an ANSI-standard SQL definition for all computer systems." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A language used to insert, retrieve, modify, and delete data in a relational database. SQL also contains statements for defining and administering the objects in a database." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A language used to insert, retrieve, modify, and delete data in a relational database. SQL also contains statements for defining and administering the objects in a database. SQL is the language supported by most relational databases, and is the subject of standards published by the International Standards Organization (ISO) and the American National Standards Institute (ANSI). SQL Server 2000 uses a version of the SQL language called T-SQL." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

 "An industry standard English-like language for building and manipulating relational databases." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"Originally developed by IBM, this is a standards-based language that allows access to information stored in a relational database. See also Transact-SQL." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"The language understood by RDBMSs and used to create and manage database objects and perform data manipulations (INSERT, UPDATE, DELETE, and SELECT queries). SQL Server uses a version of the SQL language called Transact-SQL." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"The programming language used to access data stored in a relational database." (Laura Reeves, "A Manager's Guide to Data Warehousing", 2009)

"A standard computer language designed to query any OLTP database, regardless of operating system." (Ken Withee, "Microsoft® Business Intelligence For Dummies®", 2010)

"A database query and programming language widely used for accessing, querying, updating, and managing data in relational database systems." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A standardized language for defining and manipulating data in a relational database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Functional Dependency (Definitions)

 "Y is functionally dependent on X if the value of Y is determined by X. In other words if Y = X +1, the value of X will determine the resultant value of Y. Thus, Y is dependent on X as a function of the value of X. Functional dependence is the opposite of determinance." (Gavin Powell, "Beginning Database Design", 2006)

"A constraint between two attributes or two sets of attributes in a relation." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A relationship between two attributes (or two combination of attributes) in a relation such that for every unique value of the second attribute, the table contains only one value of the first attribute. The first attribute, however, may be associated with multiple values of the second attribute." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The property of one or more attributes (data items) that uniquely determines the value of one or more other attributes (data items). Given a table R, a set of attributes B is functionally dependent on another set of attributes A if, at each instant of time, each A value is associated with only one B value." (Toby J Teorey, ", Database Modeling and Design" 4th Ed., 2010)

"Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given value of the attribute A determines exactly one value of the attribute B. The relationship 'B is dependent on A' is equivalent to 'A determines B' and is written as AB." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

🛢DBMS: NULL (Definitions)

"Having no explicitly assigned value. NULL is not equivalent to zero, or to blank. A value of NULL is not considered to be greater than, less than, or equivalent to any other value, including another value of NULL." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"An entry that has no explicitly assigned value. NULL is not equivalent to zero or blank. A value of NULL is not considered to be greater than, less than, or equivalent to any other value, including another value of NULL." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A possible value for any Oracle column that indicates the absence of any known value for that column. A NULL is usually used to represent a value that is unknown, not applicable, or not available." (Bob Bryla, "Oracle Database Foundations", 2004)

"A special column value that means 'this column has no value'." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"Null is a special marker used to indicate an unknown value or the absence of a value within a database." (Michael Coles & Rodney Landrum, , "Expert SQL Server 2008 Encryption", 2008)

"An entry that has no explicitly assigned value. null is not the same as zero or blank." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A value, distinct from 0 or a blank, that means 'unknown'." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"Pertaining to a value that indicates missing or unknown data." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Represents missing or unknown information at the attribute (or column) level. If an attribute (or column) 'value' can be null, it can mean one of two things: The attribute/column is not applicable for certain occurrences of the entity, or the attribute applies to all entity occurrences, but the information may not always be known. It could be a combination of these two situations, too." (Craig S Mullins, "Database Administration", 2012)

"Having no explicitly assigned value. NULL is not equivalent to zero, or to blank. A value of NULL is not considered to be greater than, less than, or equivalent to any other value, including another value of NULL." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Cartesian Product (Definitions)

"All the possible combinations of the rows from each of the tables specified in a join. The number of rows in the Cartesian product is equal to the number of rows in the first table times the number of rows in the second table. Once the Cartesian product is formed, the rows that do not satisfy the join conditions are eliminated." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

[cross join:] "When all rows from one table are joined to all rows of the other table." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"All of the possible combinations of the rows from each of the tables involved in a join operation. The number of rows in a Cartesian product of two tables, for example, is equal to the number of rows in the first table multiplied by the number of rows in the second table. Cartesian products almost never provide useful information. Queries using the CROSS JOIN clause or queries without enough JOIN clauses create Cartesian products." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[cartesian join:] "A set comprised of all the possible combinations from multiple constraints." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"The set of all ordered pairs {a, b} where a is a member of set A and b is a member of set B. In database terms, a cartesian product joins all rows in Table1 with all rows in Table2. Thus if Table1 has the values {T_a1, T_b1} and Table2 has the values {T_a2, T_b2} then the cartesian product is {(T_a1, T_a2) (T_a1, T_b2) (T_b1, T_a2) (T_b1, T_b2)}.Cartesian products are useful for explanation, but when we see an operation which 'goes cartesian', we usually criticize the optimizer. " (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A join between two tables where no join condition is specified, and as a result, every row in the first table is joined with every row in the second table." (Bob Bryla, "Oracle Database Foundations", 2004)

"A mathematical term describing a set of all the pairs that can be constructed from a given set. Statistically it is known as a combination, not a permutation. In SQL jargon, a Cartesian Product is also known as a cross join." (Gavin Powell, "Beginning Database Design", 2006)

"All of the possible combinations of the rows from each of the tables involved in a join operation." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

[cross join:] "A join that performs a relational product (also known as the Cartesian product) of two tables." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"In data processing, given two or more populations, the Cartesian product is the set of all possible combinations, taking one value from each population. Usually a large and meaningless answer set for an incorrectly phrased query. SEE ALSO query from hell." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The result of a Cartesian join, occurring when every row of one table is joined to every row of another table (or itself) without the use of join predicates." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures", 2012)

[cartesian join:] "A join in which one or more of the tables does not have any join conditions to any other tables in the statement. The optimizer joins every row from one data source with every row from the other data source, creating the Cartesian product of the two sets." (Oracle, "Database SQL Tuning Guide Glossary", 2013)