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Published byDeclan Legrande Modified over 2 years ago

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1 Assignment 4 Map entities with relationships to relational schemas. Use DBDL to describe the table schemas.

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2 E1 att1 att2: composite (att21, att22, att23) att3: multi-value (limit unknown) composite (att31, att32, att33) Note: One instance of E1 can have multiple tuples of (att31, att32, att33). Different instances of E1 could share the same tuple of (att31, att32, att33). Primary Key: att1 E1 att1 att2: composite (att21, att22, att23) Primary Key: att1 NewEntity att1 att3: multi-value (limit unknown) composite (att31, att32, att33) Primary Key: ? NewAtt

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3 E1 att1 att2: composite (att21, att22, att23) att3: multi-value (limit unknown) composite (att31, att32, att33) Note: One instance of E1 can have multiple tuples of (att31, att32, att33). Different instances of E1 could share the same tuple of (att31, att32, att33). Primary Key: att1 E1 (att1, att21, att22, att23) PK: att1 AK: NONE FK: NONE NewEntity (NewAtt, att1, att31, att32, att33) PK: NewAtt AK: None FK: att1 References E1

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4 E2 E3 A1 B1: composite (B11, B12, B13) A2 B2 Primary Key: A1 Primary Key: B1 E2 (0..*) ----- R1 ----- (1..*) E3 Attribute: D1, D2 one-to-one? one-to-many? many-to-many? NewEntity D1 D2 A1 B1 (composite) PK? PK: C (new attribute as PK)

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5 E2 E3 A1 B1: composite (B11, B12, B13) A2 B2 Primary Key: A1 Primary Key: B1 E2 (0..*) ----- R1 ----- (1..*) E3 Attribute: D1, D2 E2 (A1, A2) PK: A1 AK: NONE FK: NONE E3 (B11, B12, B13, B2) PK: B11, B12, B13 AK: NONE FK: NONE R1(A1, B11, B12, B13, C, D1, D2) PK: C (new attribute as PK) AK: NONE FK: A1 References E2 B11, B12, B13 References E3

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6 E4 E5 A3: composite (A31, A32) B3 A4 B4: multi-value Primary Key: A4 B5 Primary Key: B3 E4 (0..*) ----- R2 ----- (0..1) E5 E4 (A31, A32, A4, B3) PK: A4 AK: NONE FK: B3 References E5 E6 (B3, B4, ID) PK: ID AK: NONE FK: B3 References E5 E5 (B3, B5) PK: B3 AK: NONE FK: NONE

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