Database - Terminology

1. What is database
Database is a organised collection of some data that can be easily accessed and managed through backend of some program, website or terminal/command prompt.
To access our data we are using commands like:

• INSERT,
• SELECT,
• ORDER BY,
• DELETE,
• ETC.

This commands are easy to use because most of them are in plain english language and intuitive.
There is two types of database. Relational and not relational database.

Relational databases:

• MySQL
• SQLite

Non-relational databases:

• MongoDB
• Azure Cosmos DB

2. Benefits of using a Database

Using databases is very beneficial as DB can store info about our products, product properties and others as an example:

• Product name,
• availability,
• price,
• users,
• user privileges,
• comments,
• etc.

As database can handle simple operations, we can use it to log in user. How log in in database can look like in simple words: 

1. User inputs username and password,
2. server makes a query to database with given username and password,
3. database compares server's query with data stored in database,
4. if database found fields with that username and related to this username password, and user input is good, database will return us true value (access), else if there is no password or username related to database, then database returns false value (no access).

Another important thing about databases it their structure, which is easy to read and it assures us that no value will be redundant as if we try to insert values that already exists into our database the error will occur.

If we just have access to database we can use it in different programs as it is not designed just for one purpose or one project.



3. Different views of database
There is few types of database views.

• Structure view - how the database structure look like. How everything in database is connected with each other,
• External view - what the user of final database will see

In relational database we can connect data with nodes, which provides us more specific selection selection of data.

4. Database access levels
Database allows us to give different permissions to users or administrators. For an example users can be allowed to only read data from database and administrator will be allowed to change something in database.

Access levels is about giving different privileges to different database users.