Describe options for storing data in databases

Question 1

Define a database

Answer 1

A database is used to define a central system in which data can be stored and queried.

Question 2

What databases are there?

Answer 2

1. Relational databases
2. Non-relational databases

Question 3

What is a relational database?

Answer 3

• Commonly used to store and query strucutred data stored in tables that represent entities. Each entity instance is assigned a primary key that uniquely identifies it and used to reference the entity to other tables.
• This use of keys reference data entities enables a relational database to be normalized - elimination of duplicate data values.
• Tables are managed and queried using Structured Query Language (SQL).

Question 4

What is a non-relational database?

Answer 4

Are data management systems that d**on’t apply a relational schema **to the data. Often referred to as NoSQL database.

Question 5

What are common non-relational databased used?

Answer 5

1. Key-value databases: each record consists of a unique key and an associated value in some format.
2. Document databases: a specific form a key-value databases in which the value is a JSON document.
3. Column family database: store tabular comprising of rows and columns, but the columns are grouped into column-families which are logically related.
4. Group databases: store entities as nodes with links to define relationships between them.