Databases Flashcards
What is a flat file?
Consists of information about a single netity
What is an entity?
A category of object, person, event or thing about which data needs to be recorded.
What is an identifier?
Something which uniquely identifies a particular record.
What is the identifier in a relational database?
Primary key.
What is a composite primary key?
Two or more attributes needed to uniquely define a record.
What is each entity represented by?
A table
What are relations?
Tables in a database
What does a database contain?
One or more relations
What does each row contain?
Records.
What do the columns in each relation contain?
Fields belonging to the records
What is a foreign key?
- An attribute that creates a join between two tables
* It is the primary key in the first table
What does referential integrity mean?
No foreign key in one table can reference a non existent record in a related table.
