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Add DB concepts section #112

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9 changes: 9 additions & 0 deletions backend/database/README.md
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## QUESTIONS

- What is a database (DB)?
It is an electronically stored collection of data
- What is a column? A row? A table? What do these represent?
It is a category of a table in a database. A row represents an entry or data record. A table is a structured way to store rows and columns.
- What is a primary key? Why is it important?
It is a unique identifier for a row and it is important because it ensures a unique entry in a table
- What is the difference between a SQL DB, NoSQL DB, and Graph DB?
SQL databases require a fixed table schema, while NoSQL databases do not. Graph DBs prioritize the relationship between different data records
- What is data persistence? Why is it important?
It is the ability of an application to save data so that it can be retrieved and used at a later date, even if the system has been restarted or closed.
- What is a data model?
A strutured way of organizing data and defining how it is stored and accessed
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Typo: Replace 'strutured' with 'structured'.

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A strutured way of organizing data and defining how it is stored and accessed
A structured way of organizing data and defining how it is stored and accessed

- What is an ORM?
An object-relational map is a tool that allows developers to interact with a relational database through objects in code.

## ADVANCED

- What is 3rd Normal Form (3NF)?
3NF is a stage in database normalization used to design relational database tables to minimize data redundancy and ensure its integrity.
- What are the three types of relationships in a relational database, and what’s the difference between them?
one to one, one to many, and many to many. In one to one. In a one to one relationship, one row in a table is linked to a row in another. In a one to many relationship, one row in a table is linked to many rows in another. Finally, a many to many relationship has multiple rows in one table connecting to many rows in another table.
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Rephrase the relationship explanation for clarity; remove the redundant fragment 'In one to one.'

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one to one, one to many, and many to many. In one to one. In a one to one relationship, one row in a table is linked to a row in another. In a one to many relationship, one row in a table is linked to many rows in another. Finally, a many to many relationship has multiple rows in one table connecting to many rows in another table.
one to one, one to many, and many to many. In a one to one relationship, one row in a table is linked to a row in another. In a one to many relationship, one row in a table is linked to many rows in another. Finally, a many to many relationship has multiple rows in one table connecting to many rows in another table.


## RESOURCES

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