File access Flashcards
What is file access?
How data is stored and accessed
What is serial access?
Records are written one after another (you have to start with the first record and go on until the required is reached) - takes a long time.
What two methods are quicker than serial access?
-Indexed sequential
-Direct access
What is indexed sequencial file access?
-files are stored one after another, but ordered based on a field eg. Data about a customer might be stored in order of customer ID.
-it’s useful when batch processing
Batch processing : what are master files + transaction files?
-Master files store data about one thing.
-Transaction files store data about an event e.g. an order placed.
What does indexed sequential file access involve the use of?
-It involves the use of an index based on a field to sort the data.
-Within an index is known as a secondary key.
-the index files, stores, each secondary key value, and the address in storage where the first record containing the value is stored.
-to find a record, a search is done.
what is direct file access?
-records are stored in a random order with no sequence.
-When storing the data and #algorithm [calculation) is used and performed on the key field (determines storage address).
-when searching, the same #algorithm is used - (will be used to find storage address).
-the computer system can then directly access the file/records without having to go through other records.
What is MIS?
EF:Essential feature
-MIS – management information systems
-e.g. SIMS – school management information system
-it allows/support managers in making decisions and taking action EF
-Data collected in a database EF (data is interconnected from different sources EF).
-Might use additional software to analyze data – e.g. spreadsheet
-Use of additional software known as ELS (executive information system)
-Data is presented as charts/graphs/reports. Summary.
