Explain of tables and all databases can store

Explain the features of a
relational databases Task 1 – P1

 

 

Introduction

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Purpose of database

 

 

 

 

Main features of relational
databases

 

Entities – the use of tables is to store data to be
viewed at a later data if needed within the database. The data can be stored in
countless amounts of tables and all databases can store a lot of tables.

 

 

Attributes – a Attribute that is made up of a piece of
data/information inside a record which would be called a “record”.

 

 

Data types – Databases are permanently kept as data to make
sure that the data is more efficient and also the different types of data can
normally be classed as a certain ‘data types’. The main data types are:

 

 

Field size –

 

 

Validation –

 

 

Primary key – Primary keys are unique numbers given
to each individual in a database (or if it is to do with stocking, a primary
key would be given to each item on the stock list). They are given in order to
identify a person or product, so for example when customers are entered into a
database, as they are each given unique numbers, if a customer were to ring in
and request information, they would be asked to give their primary key number
to identify them (instead of having the organisation to search for the hundreds
of people with the same names as them).

 

Foreign
keys – Foreign keys link tables together. A
primary key would be used in one table, and if used in another table, as it
will be identical, once linked together they will be known as foreign keys. For
example, if another table is made using new and current primary keys, it is
best that if one item (or customer) in the table remains with the primary key
in which they were issued (which then makes it a foreign key in the new table
as it would be linked to where it came from) so that no confusion could be
made, and also so that a second key is not made for that same item.