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An entity–relationship model (or ER model) describes interrelated things of interest in a specific domain of knowledge. A basic ER model is composed of entity types (which classify the things of interest) and specifies relationships that can exist between entities (instances of those entity types).
Chen's main contributions are formalizing the concepts, developing a theory with a set of data definition and manipulation operations, and specifying the translation rules from the ER model to several major types of databases (including the Relational Database). He also popularized the model and introduced it to the academic literature.
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)
EER-Tutor [60] is a constraint-based tutor (developed by ICTG) that teaches conceptual database design using the Entity Relationship model. An earlier version of EER-Tutor was KERMIT, a stand-alone tutor for ER modelling, which resulted in significant improvement of student's knowledge after one hour of learning (with the effect size of 0.6).
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Three employees at a Maryland Cracker Barrel have reportedly been dismissed after staff refused to seat a group of students with special needs on Dec. 3 Superintendent of Charles County Public ...
A sample ER diagram. Database requirements for a CD collection in EXPRESS-G notation.. In 1976, an entity-relationship (ER) graphic notation was introduced by Peter Chen.He stressed that it was a "semantic" modelling technique and independent of any database modelling techniques such as Hierarchical, CODASYL, Relational etc. [2] Since then, languages for information models have continued to ...
OPEC+ faces a major oil oversupply in 2025, challenging production increases. The coalition has tried to boost oil prices by holding back output. Instead, members are ceding control to non-OPEC ...