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OMIS - Moving from Logical Model to Physical ModelMigration...

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Moving from Logical Model to Physical Model…Migration Options Entity to Table "Survival" Guidelines An Entity Should Survive as/into a Table if: - There are Columns that Describe the PK of the Table. - There is a Business Reason (Business Rule) to Rationalize the Table. Logical Data Model Physical Data Model Scenario 1 T1-Parent T2-Child E1 E2 PK PK OR T1 PK Scenario 2 T1-Parent T2-Child E1 E2 PK OR T1 PK One Table with PK Tied Back to PK. Scenario 3 T1-Parent E1 E2 PK AT1-Child PK(comp) T2-Parent PK OR T1-Parent AT1-Child PK PK(comp) T2-Parent PK Scenario 4 E1 E2 E3 FK in Child may be either the Child PK or Another Non-PK column in Child table. One Table with ALL Columns from BOTH Entities/Tables. PK FK FK in Child may be either a Portion of the Child PK or Another Non-PK column in Child table. 1 oo An Association Table is Created. The PK of the Association Table is the PK of EACH of the Parent Tables. An Association Table is Created as Above. BUT the PK ONLY HAS ONE Parent to a Piece of the AT PK. << Table IS NOT Migrated into the Physical Model Parent Table 2 Disappears for Lack of Business Value. Business Value is with Association to Other AT PK Data. Follow the Many to Many Process Above Creating an Association Table for EACH Logical Relationship. Then Follow the "Entity to Table Survival Guidelines". 1 1 1 M M M 1 1 1 oo 1 oo 1 oo 1 oo M M M M M M
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Description What To Do… <------ Proceed to First Normal Form evaluation. First Normal Form <------ Second Normal Form <------ Third Normal Form <------ What To Do Next… 1 Confirm the PK of each table. 2 3 Un-Checked/Normalized Data Structures This is typically the starting point. This could be one entity that contains all of the data to be Normalized or it could be several to many entities that have been formulated through Logical Data Modeling and identification of the associated Business Rules. The data anomaly that 1st Normal Form has us look for…Repeating Groups. ALL entity/table(s) should be evaluated to locate any repeating groups of column/data.
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