🛢DBMS: Query Plan [QP] (Definitions)

"The ordered set of steps required to carry out a query, complete with the access methods chosen for each table." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A portion of a DBMS that determines the most efficient sequence of relational algebra operations to use to satisfy a query." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The plan produced by an optimizer for processing a query." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A query plan is a sequence of logical and physical operators and data flows that the SQL query optimizer returns for use by the query processor to retrieve or modify data." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"Once the query optimizer determines the best way to execute a query, it creates a query plan. This identifies all the elements of the query, including what indexes are used, what types of joins are employed, and more." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A sequence of logical and physical operators and data flows that the SQL query optimizer returns for use by the query processor to retrieve or modify data." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed., 2015)

[adaptive query plan:] "An execution plan that changes after optimization because run-time conditions indicate that optimizer estimates are inaccurate. An adaptive query plan has different built-in plan options. During the first execution, before a specific subplan becomes active, the optimizer makes a final decision about which option to use. The optimizer bases its choice on observations made during the execution up to this point. Thus, an adaptive query plan enables the final plan for a statement to differ from the default plan." (Oracle)

[default plan:] "For an adaptive plan, the execution plan initially chosen by the optimizer using the statistics from the data dictionary. The default plan can differ from the final plan." (Oracle)

[execution plan:] "The combination of steps used by the database to execute a SQL statement. Each step either retrieves rows of data physically from the database or prepares them for the session issuing the statement." (Oracle)

[query execution plan:] "The set of decisions made by the optimizer about how to perform a query most efficiently, including which index or indexes to use, and the order in which to join tables." (MySQL)

🛢DBMS: Network Model (Definitions)

[network database model:] "Essentially a refinement of the hierarchical database model. The network model allows child tables to have more than one parent, thus creating a networked-like table structure. Multiple parent tables for each child allow for many-to-many relationships, in addition to one-to-many relationships." (Gavin Powell, "Beginning Database Design", 2006)

[complex network data model:] "A navigational data model that supports direct many-to-many relationships." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

[simple network data model:] "A navigational data model that supports only one-to-many relationships but allows an entity to have an unlimited number of parent entities." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

[complex network data model:] "A navigational data model that permits direct many-to-many relationships as well as one-to-many and one-to-one relationships." (Jan L Harrington, "Relational Database Design and Implementation: Clearly explained" 3rd Ed., 2009)

[simple network data model:"A legacy data model where all relationships are one-to-many or one-toone; a navigational data model where relationships are represented with physical data structures such as pointers." (Jan L Harrington, "Relational Database Design and Implementation: Clearly explained" 3rd Ed., 2009)

"A data model standard created by the CODASYL Data Base Task Group in the late 1960s. It represented data as a collection of record types and relationships as predefined sets with an owner record type and a member record type in a 1:M relationship." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A DBMS architecture where record types are organized in a many-to-many structure consisting of multiple parent-child sets." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"A network model is a database model that is designed as a flexible approach to representing objects and their relationships. A unique feature of the network model is its schema, which is viewed as a graph where relationship types are arcs and object types are nodes." (Techopedia) [source]

🛢DBMS: Precision (Definitions)

"The maximum number of decimal digits that can be stored by numeric and decimal datatypes. The precision includes all digits, both to the right and to the left of the decimal point." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"The maximum total number of decimal digits that can be stored, both to the left and right of the decimal point." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The degree of detail used to state a numeric quantity; for example, writing a value to two decimal places instead of five decimal places. Contrast with accuracy." (Richard D Stutzke, "Estimating Software-Intensive Systems: Projects, Products, and Processes", 2005)

"This is the total number of digits that can be stored in an object that uses the decimal datatype." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Refers to the preciseness with which a numerical quantity is expressed." (Michael Fitzgerald, "Learning Ruby", 2007)

"In a floating-point number, the number of digits to the right of the decimal point." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"The maximum number of significant digits that can be represented" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"An attribute of a number that describes the total number of binary or decimal digits. An attribute of a timestamp that describes the total number of decimal digits in the fractional seconds part of the value." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Hash Joins (Definitions)

"A sophisticated join algorithm that builds an interim structure to derive result sets." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A method for producing a joined table. Given two input tables Table1 and Table2, processing is as follows: (a) For each row in Table1, produce a hash. Assign the hash to a hash bucket. (b) For each row in Table2, produce a hash. Check if the hash is already in the hash bucket. If it is: there's a join. If it is not: there's no join." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An efficient method of searching two tables to be joined when they have very low selectivity (i.e., very few matching values). Common values are matched in fast memory, then the rest of the data record is obtained using hashing mechanisms to access the disk only once for each record." (Sam Lightstone et al, "Physical Database Design: The Database Professional’s Guide to Exploiting Indexes, Views, Storage, and More", 2007)

"A method for joining large data sets. The database uses the smaller of two data sets to build a hash table on the join key in memory. It then scans the larger data set, probing the hash table to find the joined rows." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The hash join is based on a hash function that provides access to items in the joining data structure in constant time. A hash function maps arbitrary inputs to fixed length keys, even though the inputs might have variable lengths. The joining data structure for the hash join is a so-called hash map, which implements an associative array that maps keys to values." (Hasso Plattner, "A Course in In-Memory Data Management: The Inner Mechanics of In-Memory Databases" 2nd Ed., 2014)

 "A join in which the database uses the smaller of two tables or data sources to build a hash table in memory. The database scans the larger table, probing the hash table for the addresses of the matching rows in the smaller table." (Oracle, "Oracle Database Concepts")

🛢DBMS: Phantom read

"Occur when one transaction reads a set of rows that satisfy a search condition, and then a second transaction modifies the data (through an insert, delete, update, and so on). If the first transaction repeats the read with the same search conditions, it obtains a different set of rows." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A phenomenon that occurs when a transaction attempts to select a row that does not exist and a second transaction inserts the row before the first transaction finishes. If the row is inserted, the row appears as a phantom to the first transaction, inconsistently appearing and disappearing." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A problem arising with concurrent transactions. The Phantom problem occurs when a transaction reads multiple rows twice; once before and once after another transaction does a data change that affects the search condition in the first transaction's reads. The result is that Transaction #1 gets a different (larger) result set back from its second read. You can avoid Phantoms by using an isolation level of SERIALIZABLE." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A phantom read (or phantom row) describes the occurrence of data returned by a statement in a transaction which was not returned by an earlier statement (with the same WHERE clause) within the same transaction." (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 problem with uncontrolled concurrent use of a database that occurs when a transaction reads data for the second time and determines that new rows have been inserted by another transaction." (Jan L Harrington, "Relational Database Design and Implementation, 3rd Ed.", 2009)

"The difference in result tables that occurs when a nonserialized transaction reads the same data twice and different rows are retrieved as a result of the actions of other interleaves transactions." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"A table row that can be read by application processes that are executing with any isolation level except repeatable read. When an application process issues the same query multiple times within a single unit of work, additional rows can appear between queries because of the data being inserted and committed by application processes that are running concurrently." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Pertaining to the insertion of a new row or the deletion of an existing row in a range of rows that were previously read by another task, where that task has not yet committed its transaction." (Microsoft, "SQL Server 2012 Glossary", 2012)

🛢DBMS: Performance Baseline (Definitions)

 "A set of metrics gathered during a performance analysis process that forms the basis of a performance tuning methodology." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A baseline is a known starting point for something. In the context of the MCITP Database Developer certification, it's a known starting point for a server. For example, when creating a performance baseline, we would measure the four core resources of a system: CPU, memory, disk, and network. A performance baseline would take a snapshot of the resources (perhaps every 30 minutes) over a period of about a week. Six months later, another counter log could be created, and by comparing it to the baseline, an administrator can identify what has changed." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A baseline measurement is taken to serve as a point of comparison for subsequent measurement." (Laura Sebastian-Coleman, "Measuring Data Quality for Ongoing Improvement", 2012)

"In the context of AWR, the interval between two AWR snapshots that represent the database operating at an optimal level." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The beginning point, based on an evaluation of output over a period of time, used to determine the process parameters prior to any improvement effort; the basis against which change is measured." (ASQ)

"Benchmark used as a reference point" (ITIL)

🛢DBMS: Semantic Data Model (Definitions)

"Semantic data model provides a vocabulary for expressing the meaning as well as the structure of database data." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A design tool for databases that uses concept-level language elements. The main role of semantic models is that they can provide an abstract approach; they are easy to understand and they provide database independence." (László Kovács et al, "Ontology-Based Semantic Models for Databases", 2009) 

"A high level data model. It is usually based on concepts and it uses a graphical formalism. It contains only the key, the semantic properties of the data structure. It does not cover the details of the implementation." (László Kovács & Tanja Sieber, "Multi-Layered Semantic Data Models",  Encyclopedia of Artificial Intelligence, 2009)

"A conceptual data model that provides structure and defines meaning for non-tabular data, making that meaning explicit enough that a human or software agent can reason about it." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A semantic data model is a conceptual data model with semantic information included." (Michael M David & Lee Fesperman, "Advanced SQL Dynamic Data Modeling and Hierarchical Processing", 2013)

"The first of a series of data models that more closely represented the real world, modeling both data and their relationships in a single structure known as an object. The SDM, published in 1981, was developed by M. Hammer and D. McLeod." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" 11th  Ed., 2014)

"The development of descriptions and representations of data in such a way that the latter’s meaning is explicit, accurate, and commonly understood by both humans and computer systems." (Panos Alexopoulos, "Semantic Modeling for Data", 2020)

"The semantic data model is a method of structuring data in order to represent it in a specific logical way. It is a conceptual data model that includes semantic information that adds a basic meaning to the data and the relationships that lie between them. This approach to data modeling and data organization allows for the easy development of application programs and also for the easy maintenance of data consistency when data is updated." (Techopedia) [source]

🛢DBMS: Physical Data Model (Definitions)

"The Physical data model supports the needs of the database administrator and application developers, who focus on the physical implementation of the model in a database." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"In the ANSI four-schema architecture, this is the organization of data used to place it in specific storage media. This is in terms of 'Tablespaces', 'Cylinders', and so on." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"A model in which the physical characteristics (location, path, and format) are described for the data. Both hardware- and software-dependent. See also physical design." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"The logical data model transformed into a physical implementation using a specific DBMS product (e.g., DB2, Oracle, SQL Server, etc.)." (Craig S Mullins, "Database Administration", 2012)

"A model in which the physical characteristics (location, path, and format) are described for the data. Both hardware- and software-dependent." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management  Ed. 11", 2014)

"The physical definition of the shape and structure of data (as defined to the DBMS)" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"Model of a database expressed at platform dependent level in the way accepted by a specific database management system. Beside the data it can also contain implementation of business logic in the form of stored procedures or transaction definitions." (Iwona Dubielewicz et al, "Quality-Driven Database System Development within MDA Approach", 2015)

"In DB2 data warehousing, a metadata model that represents the tables and other objects in a database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A data model that represents the implementation of the data contained in a data structure." (IEEE 610.5-1990)

🛢DBMS: Rule (Definitions)

"A specification that controls what data may be entered in a particular column, or in a column of a particular user-defined datatype." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Objects used to enforce business policies by ensuring that data inserted into a column match a certain pattern or fall with a range of values." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A database object that is bound to a column or user-defined data type that specifies what data can be entered in that column. Every time a user enters or modifies a value (with an INSERT or UPDATE statement), SQL Server checks it against the most recent rule bound to the specified column - for example, for limit checking or list checking. Data entered before the creation and binding of a rule is not checked. Rules are supported primarily for backward compatibility." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database object that is bound to columns or user-defined data types, and specifies what data values are acceptable in a column. CHECK constraints provide the same functionality and are preferred because they are in the SQL-92 standard." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A database object that can be applied to columns or alias data types to enforce domain integrity. Is deprecated and should not be used." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"1. A database object that is bound to columns or alias data types, and specifies which data values are acceptable in a column. CHECK constraints provide the same functionality and are preferred because they are in the SQL-92 standard. 2. In Analysis Services, a rule specifies restrictions such as Unrestricted, Fully Restricted, or Custom for security read and read/write role permissions." (Microsoft Technet)

🛢DBMS: Relational Model (Definitions)

"A method of organizing data into two-dimensional tables made up of rows and columns. The model is based on the mathematical theory of relations, a part of set theory." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A model that provides a two-dimensional structure to data. The relational database model more or less throws out the window the concept and restriction of a hierarchical structure, but does not completely abandon data hierarchies. Any table can be accessed directly with having to access all parent objects. Precise data values (such as primary keys) are required to facilitate skirting the hierarchy (to find individual records) in specific tables." (Gavin Powell, "Beginning Database Design", 2006)

"A paradigm for describing the structure of a database in which entities are represented as tables, and relationships between the entities are represented by matching data." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The relational model, based on mathematical set theory, represents data as independent relations. Each relation (table) is conceptually represented as a matrix of intersecting rows and columns. The relations are related to each other through the sharing of common entity characteristics (values in columns)." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A database model based on first-order predicate logic [...]" (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures", 2012)

"A form of data where data is normalized" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"A type of model that aims to identify relationships of interest and quantify the strength of relationship between individuals or entities. Common examples include market basket analysis and social network analysis." (Evan Stubbs, "Big Data, Big Innovation", 2014)

"Data represented as a set of related tables or relations." (Jeffrey A Hoffer et al, "Modern Systems Analysis and Design" 7th Ed., 2014)

"A database model in which data and the relationships among them are organized into tables" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"Relational modeling is a popular data modeling technique to reduce the duplication of data and ensure the referential integrity of the data." (Piethein Strengholt, "Data Management at Scale", 2020)

"(1) A data model whose pattern or organization is based on a set of relations, each of which consists of an unordered set of tuples. (2) A data model that provides for the expression of relationships among data elements as formal mathematical relations." (IEEE 610.5-1990)

🛢DBMS: Table Scan (Definitions)

"A method of accessing a table by reading every row in the table. Table scans are used when there are no conditions (where clauses) on a query, when no index exists on the clauses named in the query, or when the SQL Server optimizer determines that an index should not be used because it is more expensive than a table scan." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"The means by which SQL Server searches a table sequentially without using an index. SQL Server starts at the beginning of the table and reads every row in the table to find the rows that meet the search criteria of the query." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The means by which SQL Server performs a search on a table. SQL Server starts at the beginning of the table and reads every row in the table to find the rows that meet the search criteria of the query." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"A search of an entire table, row by row." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A data retrieval operation where the database engine must read all the pages in a table to find the rows that qualify for a query." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"This is the process of scanning each extent of a table for a needed record." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"The process of examining all rows of data in a table sequentially." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

🛢DBMS: Data Type (Definitions)

"An attribute that specifies what type of information can be stored in a column or variable. System-supplied data types are provided by SQL Server; user-defined data types can also be created. See also base data type." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An attribute that specifies the type of information that can be stored in a column, parameter, or variable." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"The type of data that a column can hold. Types include numbers, fixed-length strings, variable-length strings, and so forth." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"An attribute that specifies what type of information can be stored in a column, parameter, or variable. There are two different data types: system supplied and user defined." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"Alternate form: datatype 1.A category of physical data structures with common physical properties and uses, such as numeric, alphanumeric, packed decimal, floating point, datetime, etc. 2.A set of distinct values characterized by properties of those values and by operations on those values. [ISO/IEC 11404:1996, 4.11]" (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A classification identifying one of various types of data. Each column in a physical database design must have a data type assigned. Examples include integer, character, etc." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures 2nd Ed", 2012)

"A set of possible values, together with all the operations that know how to deal with those values. For example, a numeric data type has a certain set of numbers that you can work with, as well as various mathematical operations that you can do on the numbers, but would make little sense on, say, a string such as "Kilroy". Strings have their own operations, such as concatenation. Compound types made of a number of smaller pieces generally have operations to compose and decompose them, and perhaps to rearrange them. Objects that model things in the real world often have operations that correspond to real activities. For instance, if you model an elevator, your elevator object might have an opendoor method." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

"Classifications that identify a type or types of data (such as integer), which determines the possible values for that type." (Matt Telles, "Beginning Programming", 2014)

"A description of the set of values and the basic set of operations that can be applied to values of the type" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"In SQL, a descriptor of a set of values and a set of permitted operations. A data type determines the kind of value that a column, literal, parameter, special register, or variable can have or that can be the result of an expression, a function, or a method." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Object (Definitions)

"Conceptually a container that holds data in the database. Objects have various properties including an access control list." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"One of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure. Also called a database object. In COM programming, an object has properties and methods and exposes interfaces; for example, the SQL-DMO is a hierarchy of COM objects." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An active data value that has characteristics and properties." (Greg Perry, "Sams Teach Yourself Beginning Programming in 24 Hours 2nd Ed.", 2001)

"In databases, one of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"An instance of an item of interest to the data model." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"In databases, one of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure. In object-oriented programming, an instance of a class." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A set of instructions, generated at application compilation time, that is created and managed by a DBMS. The access plan predetermines the way an application’s query will access the database at run time." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" Ed. 11, 2014)

"A database component in a database. Can also refer to the database itself." (Technet)

"A database object in a relational database is a data structure used to either store or reference data." (Techopedia) [source]

"An object in the database that can be manipulated with SQL. Schema objects such as tables and indexes reside in schemas. Nonschema objects such as directories and roles do not reside in schemas." (Oracle)

"An object that exists in an installation of a database system, such as an instance, a database, a database partition group, a buffer pool, a table, or an index." (IBM)

🛢DBMS: Recursion (Definitions)

 "Occurs when one process calls itself to run again. With triggers, it's the process of a trigger firing itself. Indirect recursion is where an update to Table1 fires a trigger that affects Table2 that fires a trigger that updates Table1 again. Direct recursion is where an update to Table1 fires a trigger that affects Table1 again that fires the trigger again." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Recursion is a method of defining functions, CTEs, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"When a function calls itself as part of its computation. A termination condition is required to prevent an infinite recursion. See also tail-call recursion." (Dean Wampler & Alex Payne, "Programming Scala", 2009)

"The process of a method calling itself." (Rod Stephens, "Stephens' Visual Basic® Programming 24-Hour Trainer", 2011)

"When a function calls itself as part of its computation. A termination condition is required to prevent an infinite recursion. You can also have cycles of recursion between two or more functions. See also tail-call recursion." (Dean Wampler, "Functional Programming for Java Developers", 2011)

"Recursion is a method of defining functions, CTEs, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide 3rd Ed", 2012)

"The act of a function being re-entered while an instance of the function is still active in the same thread of execution. In the simplest and most common case, a function directly calls itself, although recursion can also occur between multiple functions. Recursion is supported by storing the state for the continuations of partially completed functions in dynamically allocated memory, such as on a stack, although if higher-order functions are supported a more complex memory allocation scheme may be required. Bounding the depth of recursion can be important to prevent excessive use of memory." (Michael McCool et al, "Structured Parallel Programming", 2012)

"The art of defining something (at least partly) in terms of itself, which is a naughty no-no in dictionaries but often works out okay in computer programs if you’re careful not to recurse forever (which is like an infinite loop with more spectacular failure modes)." (Jon Orwant et al, "Programming Perl, 4th Ed.", 2012)

"When a function or method calls itself. In mathematical terms, this is when a function is defined in terms of itself." (Mark C Lewis, "Introduction to the Art of Programming Using Scala", 2012)

"the act of defining a function in terms of itself." ( Manish Agrawal, "Information Security and IT Risk Management", 2014)

"The type of relationship where part of the definition makes a reference to the item being defined" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"A method of defining functions, common table expressions, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

"The ability of an algorithm to call itself" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"A process in which a problem is broken down into one or more self-similar subproblems, which are then also similarly broken down, until one reaches a base case where the solution is well-defined, often by definition." (O Sami Saydjari, "Engineering Trustworthy Systems: Get Cybersecurity Design Right the First Time", 2018)

🛢DBMS: Trigger (Definitions)

"A special form of stored procedure that goes into effect when a user gives a change command such as insert, delete, or update to a specified table or column. Triggers are often used to enforce referential integrity." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A special form of stored procedure that goes into effect when data within a table is modified. Triggers are often created to enforce integrity or consistency among logically related data in different tables." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A special type of stored procedure that is set off by actions taken on a table. Triggers allow for complex relationships between tables and complex business rules to be checked automatically." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A stored procedure that executes automatically when data in a specified table is modified. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Code stored in the database that executes automatically when certain events occur. Traditionally associated only with table write events such as INSERT, UPDATE, or DELETE, newer versions of Oracle provide the ability to define triggers on views and on other system events such as logon, logoff, and system error." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A stored procedure that executes when data in a specified table is modified. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A trigger is a stored procedure that is fired when data is modified from a table using any of the three modification statements: DELETE, INSERT, or UPDATE. FOR and AFTER are synonymous, and are usually implied when referring to triggers, rather than INSTEAD OF triggers. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A chunk of code that executes when a specified event occurs, usually before or after an INSERT, UPDATE, or DELETE command." (Gavin Powell, "Beginning Database Design", 2006)

"A database method that is automatically invoked as the result of Data Manipulation Language (DML) activity within a persistence mechanism." (Pramod J Sadalage & Scott W Ambler, "Refactoring Databases: Evolutionary Database Design", 2006)

"A stored procedure that is fired when data is modified from a table using any of the three modification statements DELETE, INSERT, or UPDATE. FOR and AFTER are synonymous and are usually implied when referring to triggers rather than INSTEAD OF triggers. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A stored procedure that executes when certain conditions occurs such as when a record is created, modified, or deleted. Triggers can perform special actions such as creating other records or validating changes." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A type of stored procedure that fires in response to action on a table. DML triggers are associated with INSERT, UPDATE, and DELETE statements. DDL triggers are associated with CREATE, ALTER, and DROP statements." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Stored in, and managed by, your database server, this software is executed when a certain event occurs. These events can range from information creation or modification to structural changes to your database. When the event occurs, the trigger is executed, causing a pre-determined set of actions to take place. These actions can encompass data validation, alerts, warnings, and other administrative operations. Triggers can invoke other triggers and stored procedures." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"A stored procedure that executes in response to a Data Manipulation Language (DML) or Data Definition Language (DDL) event." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A SQL program module that is executed when a specific data modification activity occurs. Triggers are stored in the database they manipulate." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A stored procedure that can be triggered and executed automatically when a database operation such as insert, update, or delete takes place." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"A procedural SQL code that is automatically invoked by the relational database management system upon the occurrence of a data manipulation event." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A software routine guaranteed to execute when an event occurs. Often a trigger will monitor changes to data values. A trigger includes a monitoring procedure, a set or range of values to check data integrity, and one or more procedures invoked in response, which may update other data or fulfill a data subscription." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"An event that causes a handler to be run." (Jon Orwant et al, "Programming Perl, 4th Ed.", 2012)

"An event-driven specialized procedure that is attached to database tables; typically implemented to support data integrity requirements." (Craig S Mullins, "Database Administration", 2012)

"A database object that is associated with a single base table or view and that defines a rule. The rule consists of a set of SQL statements that runs when an insert, update, or delete database operation occurs on the associated base table or view." (IBM, "Informix Servers 12.1", 2014)

"A database object that is associated with a single base table or view and that defines a rule. The rule consists of a set of SQL statements that runs when an insert, update, or delete database operation occurs on the associated base table or view." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

 "A PL/SQL or Java procedure that fires when a table or view is modified or when specific user or database actions occur. Procedures are explicitly run, whereas triggers are implicitly run." (Oracle, "Oracle Database Concepts")

"A stored procedure that executes in response to a data manipulation language (DML) or data definition language (DDL) event." (Microsoft Technet,)