All relations are tables, but not all tables are relations.
A relation is a three-dimensional table.
A characteristic of a relation is that the cells of the relation hold a single value.
A characteristic of a relation is that the rows of a relation may hold identical values.
The columns of a relation are sometimes called "tuples."
A tuple is a group of one or more columns that uniquely identifies a row.
Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
The functional dependency noted as A B, means that the value of A can be determined from the value of B.
In the functional dependency shown as A B, B is the determinant.
Functional dependencies can involve groups of attributes.
A determinant of a functional dependency may or may not be unique in a relation.
A row can be uniquely identified by a key.
A key can be composed of a group of attributes taken together.
It is possible to have a relation that does not have a key.
A relation can have only one candidate key.
Surrogate keys usually slow performance.
Surrogate keys are normally not shown on forms or reports.
A constraint that requires an instance of an entity to exist in one relation before it can be referenced in another relation is called an insertion anomaly.
A referential integrity constraint limits the values of a foreign key.
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
Undesirable consequences of changing the data in a relation are called "modification anomalies."
A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.
Relations are classified into "normal forms" based on the types of modification anomalies that they are vulnerable to.
Any table that meets the definition of a relation is in 2NF.
A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.
The essence of normalization is taking a relation that is not in BCNF and breaking it into multiple relations such that each one is in BCNF.
Breaking a relation into two relations may create the need for a referential integrity constraint to be defined between the two relations.
A multivalued dependency exists when a determinant is matched to a set of values.
The multivalued dependency noted as A --> -->B, means that the value of A determines a set of values of B.
A relation is in 4NF when multivalued dependencies are isolated in their own relation.
A(n) _______ is a table composed of columns and rows.
In relational terms as defined by E.F. Codd, a row is called a(n) ________.
In relational terms as defined by E.F. Codd, a column is called a(n) _________.
A(n) __________ is a relationship between attributes such that if we know the value of one attribute, we can determine the value of the other attribute.
If by knowing the value of A, we can find the value of B, then we would say thatB is ________ on A.
In functional dependencies, the attribute whose value is known or given is referred to as the ________ .
Given the functional dependency (A, B) --> C, the attributes (A, B) are referred to as a ____________.
A --> B, A --> C
Given the functional dependency A --> (B, C), then it is true that _______ and___________ .
A -->C, B --> C
Given the functional dependency (A, B) --> C, then it is not true that _______ and ________ .
B --> A
Given the functional dependency A --> B, it is not necessarily true that _________ .
A(n) _______ is a combination of one or more columns that is used to identify particular rows in a relation.
A(n) ___________ is a group of attributes that uniquely identifies a row.
A(n) _____________is one of a group of keys that may serve as the primary key in a relation.
A(n) _______ is a candidate key that has been selected to uniquely identify rows in a relation.
A(n) relation or table has only one __________ .
A(n) ___________ is an artificial column that is added to a relation to be its primary key.
A(n) ___________ is one or more columns in one relation that also are the primary key in another table.
referential integrity constraint
A(n) ___________________ is used to make sure the values of a foreign key match a valid value of a primary key.
For some relations, changing the data can have undesirable consequences called __________________.
Relations are categorized into ____________ where the categorization is based on the problems the relation has.
Any table that meets the definition of a(n) ___________is said to be in first normal form.
If a table is a relation then it is in __________ .
A defining requirement for _____________ normal form is that every determinant must be a candidate key.
A relation is in BCNF if every _____________ is a candidate key.
A relation is in BCNF if every determinant is a(n) ____________ .
Domain/key normal form requires that every __________ be a logical consequence of the definition of domains and keys.
A relation that is in __________ normal form is assured to be free from all anomalies.
Every time we break up a relation during the normalization process, we may have to create ___________ constraints.
A relation is in 4NF if it is in BCNF and it has no ___________________.
When designing or normalizing relations, each relation should have only one ________ .