Database Concept - ERD Mapping to MS Access
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This document provides mappings from Chen's entity-relationship (ER) diagram notations to database tables. It discusses how various ER relationships such as one-to-one, one-to-many, many-to-many, weak entity, and inheritance mappings are represented in tables. Examples are given for each type of relationship such as a one-to-many relationship between a Seller and Purchase or a many-to-many relationship between a Student and the Classes they register for. Notes are included to explain considerations for representing relationships properly in tables.
Database Concept - ERD Mapping to MS Access
- 1. Oum Saokosal Master of Engineering in Information System Jeonju University, South Korea O12-252-752 Mapping: Chen ERD to Table Relationship
- 2. Notation in Chen's E-R Diagram Entity Note: An Entity in ER is an interested Entity. Relationship Weak Entity Identifying Relationship Student Register Play on
- 3. Attribute Attribute (XXX 1 1 dob) Multi-valued Attribute (XXX 1 M tel) Composite Attribute (XXX M 1 address) (XXX 1 1 address) Multi-valued Composite Attribute (XXX 1 M Category) Derived Attribute (XXX 1 1 age) dob tel address age House Street category code description
- 4. Mapping: 1-N Seller make Purchase 1 N hire_date id name tel other id date name Customer tel Note: in ER diagram, seller id is not included in the table Purchase. It is the foreign key referenced from the table Seller. However, in the table relationship, seller id has to be included the table Purchase in order to make it 1-to-M relationship.
- 5. Mapping: 1-1 Student has Profile 1 1 tel id name sex address father photo favorite other mother Note: st_id: Autonumber pro_id: Number
- 6. Mapping: M-N Student Register Class M N register date reg id tel id name sex address id name year semester capacity
- 7. Mapping: ISA Relationship Student tel id name sex address isa Bachelor Master PhD publication research thesis dissertation Note: In Student: st_id: Autonumber In Bachelor, Master, PhD: st_id: Number
- 8. Mapping: M-N Tenary Student Register Class M N register date reg idtelid name sex address id name year semester capacity Cashier name tel T
- 9. Mapping: M-1 Unary (1) Employee tel id name sex address Report to M 1 Cannot enter 4 in table em_report_to because no em_id = 4 yet.
- 10. Mapping: M-1 Unary (2) SELECT S.em_id, S.em_name AS Boss, T.em_id, T.em_name AS Staff FROM tbl_employee AS S, tbl_employee AS T WHERE S.em_id = T.em_report_to;
- 12. Oum Saokosal Master of Engineering in Information Systems, Jeonju University, South Korea 012-252-752 oum_saokosal@yahoo.com End of Chapter