Relational Databases
Second Normal Form is designed to
ensure that every non-key field in a record is fully functionally dependent upon the key for that record
What does 3NF ensure?
ensure that there is no dependencies between non-key fields
Is a many-to-one relationship the same as a one-to-many?
yes
Is it possible for a table to have more than one foreign key?
yes a table can have more than one foreign key
A relation is in 1NF if it doesn't contain any ____________?
duplicate rows, repeating fields in a table values are atomic
What are the stages of Database Normalization?
first, second, and third normal form
What is the name of a field in a table that relates to the identifier in another table?
foreign key
A foreign key must
have either a matching value in the referring (primary) table
What are some properties of a relational database
in relational databases, each column should have a unique name
What is a many to many relationship
is not permitted in relational database design
What is a transitive dependency?
is when field A depends on field B and field B is not a key field
what is a database schema
it is a collection of database objects: tables, columns, primary and foreign keys, relationships between tables, stored procedures and views
Which type of relationship uses a junction (intermediary) table?
many to many
If attribute of relation schema R is not a member of some candidate key then this type of attribute is classified as
non prime attribute
What are the three main data types used when designing a database?
number, date, and text
A relationship that is rarely seen in real life is a
one to one
What are some valid types of relationships in a Relational Database?
one to one, many to one, many to many
Which of the following are benefits of a well-designed database?
prevents duplicate data, easy to expand in the future, can help retrieve data retrieval speed
what is the name of a field or set of fields used to uniquely identify a record in a table
primary key
What do the lines between tables (or entities) on a database diagram mean?
relationships between tables
What do the lines between tables (or entities) on a database diagram mean?
relationships between two tables
what are the table rows also called
table rows are also called tuples and records
Consider the following table which of the following affirmations applies the best:ID(Key Field) | FIRSTNAME | LASTNAME | BIRTHDATE | GENDER | CITYOFBIRTH | STATE
the table is in second normal form
Most Relational Database Designers will accept that in order to deal with the complexities of "real life" data modeling, a design needs to reach
third normal form
The mapping of relationship depends on
type of relationship
A one to many relationship (table A is in a one to many relationship with table B) is
where each record in table A can have one or more matching records in table B
which of the following to a valid key field
a car registration number
What is a Relational Database?
a collection of two or more tables that are joined using relationships
An Entity is a _________
a modeled thing from the real world
examples of the database
a phone contact list, a personal diary, a University Students records
What is Database Normalization?
a process whereby the design of a table (relation) is decomposed into more tables that more precisely fit the relational model
In database terminology which of the following are true
a row (record) is called a tuple, a column (field) is called an attribute, a table is called a relation
An atomic field is
a singled valued field
a table
a table consist of rows and columns
What are attributes?
another name used for a column
What are other names used for columns?
attributes and fields
If there is more than one key for relation schema in DBMS then each key in relation schema is classified as
candidate key
a DBMS stands for
database management system
