Databases

Question 1

What is a relational database?

Answer 1

A relational database consists of a set of
relations. A relation has two things in one: a schema and an instance of the schema.

Question 2

What is a schema?

Answer 2

schema defines the relation and an instance is the content of the relation at a given time.

Question 3

What does an integrity constraint do?

Answer 3

Imposes a condition that all legal instances of the relations must satisfy.

Three types: domain, primary key, foreign key.

Question 4

What are domain constraints?

Answer 4

Specify the permissible values for an attribute.

Question 5

What is a primary key?

Answer 5

Candidate keys designated by database designer. Often used to identify tuples i a relation.

The primary key constraint specifies that the primary key value of a tuple cannot be null and no two tuples
in the relation can have the same value on the primary key

Question 6

What is a foreign key?

Answer 6

Primary key in another table.

Question 7

What does JBDC stand for?

Answer 7

Java
DataBase Connectivity

Question 8

What does the SQL SELECT statement do?

Answer 8

Used to retrive rows in a table.
SELECT Columns FROM Table

Question 9

What do you use the WHERE clause for?

Answer 9

The WHERE clause can be used with the SELECT statement to specify a search
criteria