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- 1Databaseis an organised collection of related data. It is possible to add, edit, manage and retrieve data from a database. The structure of a database allows data to be found and used quickly.
- 2files records• A field is a single item of data within a record.
• A record consists of a collection of related fields.
• A file (Known as a table in Microsoft Access) is a collection of related fields. - 3Example of a field e.g.• surname: text
• date of birth: date/time
• selling pricing: currency - 4• Example of a record:• Pupil’s record in a school database only has the fields related to that pupil (surname, forename, date of birth, from, etc.) and not another pupils data.
- 5• Example of a file / table:• The table of records of all pupils in the school.
- 6Key FieldA Key fields uniquely identities each record. No two records have the same data in their key field. Also known as Primary Key.
- 7ValidationData entered in to a database must be sensible or we get GIGO.
Validation methods can only ensure reasonable and sensible data is input in to a system, but there is no certainty that the data is correct. - 8ReportsA report is a printed document that contains data from the database, organised and analysed in a certain way. A report from a student database might list the students in each class in alphabetical order.
- 9FormsForms are used to make data entry more attractive and secure rather than entering data into raw tables.
- 10Calculated fieldsNot all data needed in a report may be present in a database. For example a person’s age is never included because it changes day by day. If you want to use age in a report it must be calculated. This result is known as a calculated field.
- 11Uses of a database• Add, change or delete records
• Search for a particular record
• Sort the records into a given order
• Print reports about some aspect of the database - 12Updating records• Add a new record when a new pupil arrives to a new school
• Edit existing records when someone move house
• Delete an old record when an employee leaves a job - 13Simple query serachlooks for data in one field.
Complex query search – looks at data with multiple criteria. - 14Complex query searchlooks at data with multiple criteria.
- 15Wildcard charactersYou use wildcard searches in a query for data that you only know part of. For example find all the surnames beginning with ‘S’ you might write:
surname LIKE “*S” - 16Sorting dataResults of queries can be presented in a sorted order e.g. alphabetical or in numerical order. Sorts can also be in ascending (A-Z) or descending (Z-A) order.
- 17Physical securityo Locks on doors
o Alarms
o ID cards
o Biometric systems - 18Passwordo Authorised users are given a username. Each user also has a password that proves the user is really the one whose username is given.
o Using passwords is a method of authentication. - 19Access rights (file attributes) can be places on individual files to giveo No right to access the file
o Read access (user can view file but not alter it)
o Write access (allowing the user to alter the contents of the file) - 20Backups Saved on to removable media (CD, DVD, memory sticks)
Stored at a separate location in a locked room or fireproof safe.
Made regularly (every day) - 21Benefits of using a databaseValidation: you can set checks on the data being entered to ensure no inappropriate data gets into the system.
Reports: results of searches can be used to print reports that may help management in their decision making.
Sharing: database can be shared with any number of users on a network. Any user can edit the data.
Security: passwords may be set so that no unauthorised user can access the database, which may contain personal and sensitive data.
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- Fichas sobre Sin título, creado por leef033 el 19/01/2015.
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