ICT - Databases

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  • Created by: lou9119
  • Created on: 24-04-16 11:32
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  • Databases
    • - A database is an organised collection of related data that can be added, edited and managed.
    • Data Types
      • Number integer i.e 43.
      • Number real i.e 43.25
      • Text or string i.e John Smith.
      • Curency
      • Boolean i.e yes
      • Lists
      • Picture
      • Sound
      • Video
    • Files, records and fields
      • Field: A single data item.
        • Record: A collection of related fields.
          • File:A collection of related records, sometimes referred to as tables.
            • Files, records and fields
              • Field: A single data item.
                • Record: A collection of related fields.
                  • File:A collection of related records, sometimes referred to as tables.
                    • Updating records is key, some examples in a school system are adding new records when a pupil joins, edit records if a pupil's information change and delete records when a pupil leaves.
                  • A KEY FIELD uniquely identifies a record. Meaning that no two records will have the same key field. The purpose of this is to be able to refer to an individual record using a single field.
            • Updating records is key, some examples in a school system are adding new records when a pupil joins, edit records if a pupil's information change and delete records when a pupil leaves.
          • A KEY FIELD uniquely identifies a record. Meaning that no two records will have the same key field. The purpose of this is to be able to refer to an individual record using a single field.
      • Validation
        • -GIGO, checks are done to make sure the data inputted is correct.
          • Range check = data is within a sensible range.
          • Type check = data is of the correct type.
          • Length check = length of the input for the number of characters is used.
          • Look-up-list = data entered against a list of possible entries.
          • Picture or format check = data entered has a particular pattern.
          • Input mask = forces data to conform to a rule.
          • Presence check = ensures that certain data is present.
      • Reports
        • - A printed document that contains data from the database, organised and analysed in a certain way.
      • Calculated fields
        • - Not all data needed in a report may be presented from the database, For example a person's age changes every day and so if you want to use age in a report you must you a calculated field.
      • Uses
        • Add, change or delete records.
        • Search for records.
        • Sort records in a given order.
        • Print reports.
        • Use the data for applications.
      • Sorting
        • Alphabetical order for a register.
        • Order of marks in an exam.
        • Chronological order for D,O.B
        • Searching for Data
          • - By creating a query you can search for specific fields. This can be done by using a simple search (looking for data in only one key field) or a complex search (looking for data with multiple criteria.
            • Wildcard characters are used in a query to stand for any character you don't know exactly. For example you may search: Surname LIKE "S"
          • Operators can be used for this also. i.e =, , , AND, OR
      • Benefits
        • Fast
        • Data integrity
        • Print reports
        • Shared on networks
        • Passwords
          • Method  of AUTHEN-TICATION.
            • Acces rights also can be placed on a file to give either no right to access, read access or write access.
      • Security and databases
        • If it is secure it cannot be destroyed, altered or get into unauthorized hands.
        • Physical security can be set in place too, locks, alarms, ID cards and biometric systems.
        • Backups
          • This can be done through removable media (memory stick) stored in a safe or made regularly.

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