Figure 2 11c shows how asso ciative entities are

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Nature of Mathematics
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Chapter 5 / Exercise 6
Nature of Mathematics
Smith
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because the associative entity represents the relationship. Figure 2-11c shows how asso-ciative entities are drawn using Microsoft Visio, which is representative of how youwould draw an associative entity with most E-R diagramming tools. In Visio, the rela-tionship lines are dashed because CERTIFICATE does not include the identifiers of therelated entities in its identifier. (Certificate Number is sufficient.)
How do you know whether to convert a relationship to an associative entity type?
ABEMPLOYEEEmployee ID Employee Name(...)Birth DateCOURSECourse ID Course Title{Topic}Certificate Number Date CompletedCERTIFICATEFIGURE 2-11(continued)Employee IDPKEmployee NameEMPLOYEECertificate NumberPKDate CompletedCERTIFICATECourse IDPKCourse TitleCOURSE(b) An associative entity (CERTIFICATE) (c) An associative entity using Microsoft VISIO
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Nature of Mathematics
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Chapter 5 / Exercise 6
Nature of Mathematics
Smith
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Chapter 2Modeling Data in the Organization81DegreeThe number of entity types thatparticipate in a relationship.relationship (Completes in Figure 2-11a) as two one-to-many relationships (the ones asso-ciated with CERTIFICATE in Figures 2-11b and 2-11c).Notice that converting a relationship to an associative entity has caused the rela-tionship notation to move. That is, the “many” cardinality now terminates at the associa-tive entity, rather than at each participating entity type. In Figure 2-11, this shows that anemployee, who may complete one or more courses (notation A in Figure 2-11a), may beawarded more than one certificate (notation A in Figure 2-11b); and that a course, whichmay have one or more employees complete it (notation B in Figure 2-11a), may havemany certificates awarded (notation B in Figure 2-11b). See Problem and Exercise 18 for

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