DATABASES

persistent and structured collection of data

Single unit in a database, made up of fields (name ,Id,etc)

Change in state of a database

A file of events

Principal file that stores basic details about a business (eg supermarket stock)

One table in the database, no other tables

Any thing represented in a database like a student or bag

Database with one or more tables with unique keys to provide a relations between data

Same as record

Unique key to a row

A field repeated from another table

Additional key used with the primary key to locate a piece of data, narrowing down the data. It’s not unique but it is unique to a smaller number of fields making the search possibly faster

Unnecessary repeated data

Where collection of data is gradually (in 3 steps) organised into tables to remove data redundancies

No duplicate columns Has primary key Data is atomic

1NF every field is dependent on the primary key

2NF No transitive dependencies, fields cannot depend on a non key field NO MANY TO MANY RELATIONSHIPS

Combination of multiple keys, eg first and surname

DB must be able to have create read update and delete rows

Processing which provides a response to a user in a short time

Data is intended and is fit for purpose

Ensuring that changes in a database are consistent (so) if a record is removed all references are also removed

ATOMICITY - changes in a database are performed, or not performed CONSISTENCY - constant state of the database before and after ISOLATION - transactions are performed in isolation, so nothing can interrupt it, only until data has been committed DURABILITY - once A change is made is must not be lost

SELECT “NAME”, “ADDRESS” FROM “Customers” WHERE “Name” = “Cox”;