What is a database?
A database is a collection of data organised in a way that makes it easy for a computer program to search and store information. You can think of it like an electronic filing system.
Where are databases used?
Databases are used in many different settings, for different purposes. A social network will use a database to store information about you, your friends, places you have visited or posts you have liked. Libraries will use databases to keep track of which books are available and which are out on loan.
Database concepts
A database is a persistentData will still be stored if the computer is turned off, organised store of data, meaning it will exist even when the power is off or the system has a failure.
Organisation of data
Data is organised into a tableContain all the fields and records for one particular collection of entities in a database. structure. A table is a collection of records, with each recordAll of the data relating to one entity in a database. stored as a row. Each record is a collection of information called attributes or fieldAn element of a database record in which one piece of information is stored. For example 'name' in an electronic address book..
The table below has five records. Each record has six attributes. Customer ID is a primary keyThe unique identifying value for records in a database..
| Customer ID | First name | Last name | Gender | Address | Town/city |
| C0 | Alice | Anderson | F | 13 Monk Way | Lisburn |
| C1 | Bob | Buchannon | M | 14b Iris Street | Belfast |
| C2 | Conor | Crawley | M | 17 Eblana Street | Armagh |
| C3 | Davina | Devlin | F | 53 Fitzwilliam St | Newry |
| C4 | Edward | Ellison | M | 42 Park View | Enniskillen |
| Customer ID | C0 |
|---|---|
| First name | Alice |
| Last name | Anderson |
| Gender | F |
| Address | 13 Monk Way |
| Town/city | Lisburn |
| Customer ID | C1 |
|---|---|
| First name | Bob |
| Last name | Buchannon |
| Gender | M |
| Address | 14b Iris Street |
| Town/city | Belfast |
| Customer ID | C2 |
|---|---|
| First name | Conor |
| Last name | Crawley |
| Gender | M |
| Address | 17 Eblana Street |
| Town/city | Armagh |
| Customer ID | C3 |
|---|---|
| First name | Davina |
| Last name | Devlin |
| Gender | F |
| Address | 53 Fitzwilliam St |
| Town/city | Newry |
| Customer ID | C4 |
|---|---|
| First name | Edward |
| Last name | Ellison |
| Gender | M |
| Address | 42 Park View |
| Town/city | Enniskillen |
Each record must be uniquely identified in order to access individual record details. A primary key is a unique value used to identify each record in a database. This could be a Customer ID in a shop database or a patient ID in a doctor's surgery.