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  2. Python syntax and semantics - Wikipedia

    en.wikipedia.org/wiki/Python_syntax_and_semantics

    In all versions of Python, boolean operators treat zero values or empty values such as "", 0, None, 0.0, [], and {} as false, while in general treating non-empty, non-zero values as true. The boolean values True and False were added to the language in Python 2.2.1 as constants (subclassed from 1 and 0 ) and were changed to be full blown ...

  3. Name–value pair - Wikipedia

    en.wikipedia.org/wiki/Name–value_pair

    Example of a web form with name-value pairs. A name–value pair, also called an attributevalue pair, key–value pair, or field–value pair, is a fundamental data representation in computing systems and applications. Designers often desire an open-ended data structure that allows for future extension without modifying existing code or data.

  4. Value object - Wikipedia

    en.wikipedia.org/wiki/Value_object

    In C#, a class is a reference type while a struct (concept derived from the struct in C language) is a value type. [5] Hence an instance derived from a class definition is an object while an instance derived from a struct definition is said to be a value object (to be precise a struct can be made immutable to represent a value object declaring attributes as readonly [6]).

  5. Attribute (computing) - Wikipedia

    en.wikipedia.org/wiki/Attribute_(computing)

    An attribute in a relational database can be represented as a column or field. In computing, an attribute is a specification that defines a property of an object, element, or file. It may also refer to or set the specific value for a given instance of such. For clarity, attributes should more correctly be considered metadata. An attribute is ...

  6. Relation (database) - Wikipedia

    en.wikipedia.org/wiki/Relation_(database)

    An attribute is a name paired with a domain (nowadays more commonly referred to as a type or data type). An attribute value is an attribute name paired with an element of that attribute's domain, and a tuple is a set of attribute values in which no two distinct elements have the same name. Thus, in some accounts, a tuple is described as a ...

  7. Candidate key - Wikipedia

    en.wikipedia.org/wiki/Candidate_key

    The set of all candidate keys can be computed e.g. from the set of functional dependencies.To this end we need to define the attribute closure + for an attribute set .The set + contains all attributes that are functionally implied by .

  8. Entity–attribute–value model - Wikipedia

    en.wikipedia.org/wiki/Entity–attributevalue...

    An entity–attributevalue model (EAV) is a data model optimized for the space-efficient storage of sparse—or ad-hoc—property or data values, intended for situations where runtime usage patterns are arbitrary, subject to user variation, or otherwise unforeseeable using a fixed design. The use-case targets applications which offer a large ...

  9. Object–relational database - Wikipedia

    en.wikipedia.org/wiki/Object–relational_database

    The characteristic properties of ORDBMS are 1) complex data, 2) type inheritance, and 3) object behavior. Complex data creation in most SQL ORDBMSs is based on preliminary schema definition via the user-defined type (UDT). Hierarchy within structured complex data offers an added property, type inheritance. That is, a structured type can have ...