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Posted by sqlservernewbie on 04/12/07 15:19
Hi Everyone,
Here is a theoretical, and definition question for you.
In databases, we have:
Relation
a table with columns and rows
Attribute
a named column/field of a relation
Domain
a set of allowable values for one or more attributes
Tuple
a row of a relation
Degree
the number of attributes a relation contains
Number of fields in a table
Cardinality
the number of tuples/rows a relation contains
But!
What is the definition for the number of unique values in a field?
So, if you have 100 rows in a table, and the field is
the gender field, with only values of: Y, N.
You have 2 unique values.
What do we call this concept?
"the number of unique values in a column?"
Is there one?
Thanks a lot!
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