- Integrity Constraints
- Key: Every relation has a primary key
- Entity Integrity: Value of primary key in a row is never undefined
- Referential Integrity: Value of an attribute of a
Foreign Key must appear as a value in the primary key of another
relationship or must be null
- Normal Forms (NF) for Relational schema
- Reduce data redundancy and facilitate querying
- 1st NF: Each column in a relation contains an atomic value
- 2nd and 3rd NF: Values of
non-key attributes are fully determined by the values of the primary
key, only the primary key, and nothing but the primary key
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Última modificación: Wednesday, 16 de November de 2005, 18:52