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Ch.2 Data Organization and Data Control - Coggle Diagram
Ch.2 Data Organization and Data Control
Data Input and Sources of Error
Transposition error
Data source error
Transcription
garbage-in-garbage-out (GIGO)
Erroneous data always produces inaccurate information, waste
Waste human resources _ while producing useless information.
Data Control
Field length check
Range check
Field presence check
Fixed value check
Format check
Type check
Check digit
Data control
Data validation
Data verification
Data Hierarchy
Field
Record
Table
Database
Database Management System (DBMS)
Small office and personal use
Database server
Creative table
Modify table
Delete table
filter
sort
Index
Data Entry Forms
Query Forms
Reports
File Access Modes
Sequential Access Mode : Magnetic tape
Data records are stored one by one along the lengthy magnetic strip
Mainly used for backing up and recording of database and data files in computer servers
Direct Access Mode: hard disk, optical disk and floppy disk
The most common storage medium for secondary storage due to its high reliability , speed and capacity
Once the target location is moved under the read/write head, the read/write operations can proceed.