"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)
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