Entity Relation_tutorial Computer Science

134 Part II Database Analysis and Logical Designmany, and a speciic number. The minimum cardinality constraint is also reerred to as the participation con-straint. A minimum cardinality o zero speciies optional participation, whereas a minimum cardinality o one speciies mandatory participation.Because many databases need to store the value o data over time, modeling time-dependent data is an important part o data modeling. Data that repeat over time may be modeled as multivalued attributes or as separate entity instances; in each case, a time stamp is necessary to identiy the relevant date and time or the data value. Sometimes separate relationships need to be included in the data model to represent associations at di-erent points in time. The recent wave o inancial report-ing disclosure regulations have made it more important to include time-sensitive and historical data in databases.Associative entity 112Attribute 105Binary relationship 116Business rule 96Cardinality constraint 119Composite attribute 106Composite identiier 108Degree 114Derived attribute 107Entity 101Entity instance 101Entity-relationship diagram (E-R diagram) 92Entity-relationship model (E-R model) 92Entity type 101Fact 99Identiier 107Identiying owner 102Identiying relationship 103Maximum cardinality 119Minimum cardinality 120Multivalued attribute 107Optional attribute 105Relationship instance 111Relationship type 111Required attribute 105Simple (or atomic) attribute 106Strong entity type 102Term 99Ternary relationship 116Time stamp 122Unary relationship 115Weak