Relational Databases

Mind Map by , created over 5 years ago

A Mind Map containing a compacted verion of everything you need to know for relationa database.

Created by BadSideSecret over 5 years ago
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Relational Databases
1 File
1.1 Table
1.1.1 Record All data about one person or thing. Quite a few fields can be used to make a record e.g. name, address,age,date of birth.
1.1.2 Field Primary Key A field in a table which is unique and this helps to identify records or people Referential integrity Every foreign key value has a matching value in the appropriate primary key field. A piece of data related to a person or thing Foreign keys A primary key in one table inserted as a normal field in another table Attributes- Name,Age,Address
1.1.3 Records are stored in here.
1.1.4 Made of quite a few pieces of information, e.g. First Name, Address, Age
1.1.5 Entities- objects,people,things
1.1.6 RelationShips: One to Many Where one entity can have many relations- such as 1 doctor has many patient or 1 student has many exams Many to many where many entities can have many relationships e.g. 1 video can be hired by several customer BUT those customers can hire several videos One to One When one entity can only be related to one entite e.g. 1 man has 1 wife.
1.2 Many tables are stored in a file, this is the database.
2 Vast amounts of info can be stored!
3 Queries can be run to search for specific records.
3.1 Searching is what a query does.
3.1.1 Parameters are just search criteria
3.1.2 4 Types Static-the parameters stay the same for ever. Dynamic- you can change the search result sto what you need Simple- only 1 parameter is used at a time Complex-more than one parameter is used
4 Reports can be created from data stored or queries run
4.1 presents data taken from a query or from tables in a preformatted attractive manner
5 Validation can be used to reduce errors.
5.1 Validation!
5.1.1 Makes sure that the data is: accurate sensible,within acceptable boundaries. Range Check- makes sure that the value entered is between 2 preset boundaries Lookup Check-Allows only a limited amount of item to be selected Length Check- checks that the data entered is a certain length. Presence check- makes sure something is enteredin the field
5.2 Verification
5.2.1 Making sure that the data on the source document is the same as the object doucument. Proof Reading- double checking your work basically. Double entry- where two people input the same document and these are then compared any differences are then noted and rectified.
6 Forms Used to enter data.
6.1 A window/Screen with multiple spaces to enter data.

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