What is a table? Answer- A table is a persistent representation of a logical relation that is a relation
whose contents can be saved for permanent
... [Show More] use.
What are the characteristics of a relational table? Answer- The characteristics of a relational table are
that a table is perceived as a two-dimensional structure composed of rows and columns, each row
(tuple) represents a single entity occurrence within the set, each column represents an attribute, each
column has a distinct name, each intersection of a row and column represents a single data value, all
values in a column must be of the same data format, the order of the rows and columns don't matter to
the DBMS, and
each table must have an attribute (or combination of attributes) that uniquely identifies each row
(tuple).
What is a tuple? Answer- A tuple is a row that represents a single entity occurrence within a set.
What are records? Answer- A record is the same as a tuple (row).
What is a field? Answer- A field is a column.
What is a key? Answer- A key consists of one or more attributes that determine other attributes. For
example, a social security number identifies all of the other attributes related to that person.
What is determination? Answer- Determination is the state in which knowing the value of one attribute
allows you to determine the value of another attribute. For example, if you know a key, you can find
other information.
What is functional dependence? Answer- Functional dependence is when knowing the value of one or
more attributes lets you know the value of the other attributes. For example, knowing the first name
and the social security number would let you find the person's last name.
What is full functional dependence? Answer- Full functional dependence is when knowing the value of
one or more attributes lets you know the value of other attributes and the value of the known attributesare NEEDED to find the other attributes. For example, a social security number lets you find the first and
last name of someone. This is full functional dependence. If it was a social security number and a first
name this would just be functional dependence because the first name is not required to look up the
last name. All you need is the SSN.
What is a determinant? Answer- A determinant is an attribute whose value determines the value of
other attributes. For example, a social security number could be the determinant for your last name.
What is a dependent? Answer- A dependent is an attribute whose value is determined by another
attribute. For example, you last name could be a dependent of your social security number.
What is a composite key? Answer- A composite key is a key that is composed of one or more attribute.
For example, the key of your last name and you social security number could be used to determine your
first name. This would be a composite key because you are using your last name and your SSN in the
key.
What is a superkey? Answer- A superkey is a key that can uniquely identify any row in a table. Some
examples of this would be your social security number identifying a row corresponding to your
information, but a superkey isn't limited to full functional dependence. Your SSN and your last name
used as a key would still be a superkey. [Show Less]