Unit 1.3.2 (Databases)

• Has a single table • • Harder to update • No specialist knowledge needed to operate • Leads to Data Redundency (same data is repeated unnecessarily multiple times)

• Has linked tables which include primary keys and forgein keys to represent relationships • Requires Specalist Knowledge through the use of SQL to create the data structures -Enforces ACID properties by making sure transactions are processed successfully

• Primary Key is a unique identifer in a table. Underlined in the entity description

• A primary key from one table used as an atttribute in another to link tables/ represent a relationship

Every foreign key value must match an existing primary key value in the related table Maintains data consistency across the data base

A one-way, non-reversible mathematical algorithm that converts an input of any size into a fixed length value.

• Some sort of change to the database. Refers to updating, inserting or deleting data

Atomic, Consistency, Isolation and Durablity

Atomic - A transaction is completly perfomed or not at all! Consistency- Ensures no transaction violates any of the defined validation rules

Isolation -Transactions happen concurrently without interfering with each other Durablity- Once a transaction is finished, its result stays saved in a non-voilatile storage, even if there is a crash or power loss

• A technique used in databases to prevent multiple users from editing the same record at the same time. This helps prevent problems like lost updates and keeps data consistent.

• All field names should be unique • Each table needs a primary key • No two records can be identical

• Must be in first normal form • Contains no partial dependencies • Has a composite key

• Must be in second normal form • Contains no non-key dependencies

A collision happens when an algorithm generates the same address for different values. Since two pieces of data cannot occupy the same physical space, the system must use a collision resolution technique

Linear Probing: Stores the hash value in the next free slot in the table Chaining: A record will point to a location in a linked list (Or start one) OverFlow Area: This will point to a Overflow Table where new items can be added, these items can still be accessed

If a hacker steals the database, they only get the hashes. They cannot reverse the hash back into the original password. Hasinng allows direct access 0(1) This means the time taken to find a record stays the same regardless of the size of the dataset

Permanently removes non-essential data from the file. The file cannot be restored to its original form, resulting in a permanent loss of quality

Reduces the file size without permanently removing any data. The original file can be fully reconstructed bit-for-bit, meaning no quality is lost.

Uses the same key for both encryption and decryption.

Uses two different keys. A public key for encryption.A private key for decryption