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  2. One-to-many (data model) - Wikipedia

    en.wikipedia.org/wiki/One-to-many_(data_model)

    In systems analysis, a one-to-many relationship is a type of cardinality that refers to the relationship between two entities (see also entity–relationship model). For example, take a car and an owner of the car. The car can only be owned by one owner at a time or not owned at all, and an owner could own zero, one, or multiple cars. One owner ...

  3. Cardinality (data modeling) - Wikipedia

    en.wikipedia.org/wiki/Cardinality_(data_modeling)

    The entity–relationship model proposes a technique that produces entity–relationship diagrams (ERDs), which can be employed to capture information about data model entity types, relationships and cardinality. A Crow's foot shows a one-to-many relationship. Alternatively a single line represents a one-to-one relationship. [4]

  4. SQL injection - Wikipedia

    en.wikipedia.org/wiki/SQL_injection

    A classification of SQL injection attacking vector as of 2010. In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker).

  5. Bijection, injection and surjection - Wikipedia

    en.wikipedia.org/wiki/Bijection,_injection_and...

    A function is injective (one-to-one) if each possible element of the codomain is mapped to by at most one argument. Equivalently, a function is injective if it maps distinct arguments to distinct images. An injective function is an injection. [1] The formal definition is the following.

  6. Associative entity - Wikipedia

    en.wikipedia.org/wiki/Associative_entity

    An associative entity is a term used in relational and entity–relationship theory. A relational database requires the implementation of a base relation (or base table) to resolve many-to-many relationships. A base relation representing this kind of entity is called, informally, an associative table. An associative entity (using Chen notation)

  7. First normal form - Wikipedia

    en.wikipedia.org/wiki/First_normal_form

    Representing relationships using foreign keys is more flexible, where a hierarchical model only can represent one-to many relationships. Since locating data items is not directly coupled to the parent-child hierarchy, the database is more resilient to structural changes over time.

  8. Anchor modeling - Wikipedia

    en.wikipedia.org/wiki/Anchor_Modeling

    An example of a knot for genders is a set of 2-tuples: { #1, 'Male' , #2, 'Female' } Static attribute tables contain two columns, one for the identity of the entity to which the value belongs and one for the actual property value. Historized attribute tables have an extra column for storing the starting point of a time interval.

  9. One-to-many - Wikipedia

    en.wikipedia.org/wiki/One-to-many

    One-to-many (data model), a type of relationship and cardinality in systems analysis; Point-to-multipoint communication, communication which has a one-to-many relationship; A one to many relation, a relation such that at least one element of its domain is assigned to more than one elements of its codomain, and no element of its codomain is ...