Features Of A Relational Database

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Features of a relational database

Primary keys:
The main feature of a relation database would be the primary key. It is a unique identifier set to each and every record that travels across different tables in relationships. An example of a primary key is a Social Security number. The primary keys job is to make each record unique and it lets data to be kept in more than one table. Each table within a relational database will have a field for the primary key. Foreign keys:
A foreign key is a column in a database that links data between tables by cross referencing because it references primary keys from other tables. For example if there are two tables, customer and order then a
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It can also be broken down into short, medium and long date/time. Date: 31/01/14, 31-Jan-14, 31 January 2014
Time: 19:24, 7:24 PM, 19:24:30
Autonumber- This will increase by 1 each time a new record is added to the database Record 1 : 1
Record 2 : 2
Record 3 : 3
Boolean (yes/no)- This is a data type that restricts the record to only two choices, either yes or no. Yes : No
On : Off

Validation rules
Validation within a database is used to make sure the data entered into the database is sensible and makes sense, also to avoid any typing errors. You make a rule which only allows certain things to be typed into the database e.g. only 11 numbers for a mobile phone number so that you don’t accidently type the wrong amount of digits. It will come up as an error if you try and then that is when you notice your mistake. Benefits
Having a relational database will greatly reduce the data redundancy because it will get rid of the repeated data within a database. This is done by going through the normalisation process and therefore since there is less data in the database it is much faster access, searching data, updating data, sorting and reporting.

Stages of normalisation
The steps of normalisation will be fully explained in the following steps: Firstly you need to turn this into a unormalised table by:
- Create column headings for the table for each data item on the report and ignore any calculated
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