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Unformatted text preview: If do not have two unique fields, can combine two fields to make one unique primary key Foreign key is an attribute that is a primary key in another table All tables have to be linked somehow Uniform table problems: o Update anomaly o Insert anomaly Null values are not good; try to have info in each space o Delete anomaly Basic requirement o Every column has a single value Primary key cannot be null, mist be unique o Entity Integrity rule Foreign key can be either null or be primary key of another table o Referential Integrity rule All non-key should describe a characteristic of object identified by the primary key...
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This note was uploaded on 05/10/2010 for the course ACG 4401C taught by Professor Oowunchekwa during the Spring '10 term at University of Central Florida.
- Spring '10