Programming 2- module 12) Flashcards
What does ‘SQL’ stand for?
Structured Query Language.
What do relational databases hold data in?
A structured format.
What does ‘DBMS’ stand for?
Database Management System.
What are relationships in a relational database?
One-to-one.
One-to-many.
Many-to-many.
What is the One-to-one relationship within a relational database?
When each entry in our student table has only one relationship in another table.
Why is the One-to-one relationship in a relational database not used much?
If there is only one link, that data could often by held on the single table.
What is the One-to-many relationship within a relational database?
Most common type of relationship: each record in one table links to one of more tables in another table, but each record in second table links to only one record in first table.
What is the Many-to-many relationship within a relational database?
When each record in one table links to one or more in the second, and vice versa.
What is the definition of a relational database?
A database that holds data in structured format identifying links between fields.
What is the definition of ‘Field’?
A single unit of data stored about an entity, stored with other fields to create a record.
What is the definition of a ‘primary key’?
Field with contents unique to each record enabling otherwise identical data records to still be separated and processed accurately.
What is the definition of a ‘foreign key’?
Primary key in one table, and included in another linked table.
What is the definition of ‘decomposition’?
Decompose data into multiple tables, to limit duplication of data entry and storage as far as possible.
What is the definition of ‘unstructured’?
No clear method of organising to the level of structured data.
