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Natural Key - A natural key is a key that has meaning. An employee's social security number might be used to uniquely identify employees in an HR system (I would NOT recommend this but I have seen it). That would be a natural key.

Normalize - To normalize a database structure means that the structure has been formatted in such a way as to facilitate SQL querying, values that are dependant on non key fields and to remove redundant (repeating) value sets.

Null - an unknown value is said to be a NULL value. An empty string has a known value (it is empty), so it is not a NULL string. Unfortuanately, Oracle treats an empty string as if it is NULL. In programming, a NULL is never equal to anything, including NULL. IF NULL == (x) is never true no matter what the value of (x).

Contact: Lewis Cunningham
lewisc@databasewisdom.com

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