Frage | Antworten |
What is an array? What is a disadvantage? | An array is a way of storing multiple types of data. A disadvantage is that it can only store 1 data type. |
What is the purpose of a record? | A record is a way of storing multiple data types under individual items of data (fields). |
What is the definition of serial files? | A collection of records, stored one after another, in no particular sequence. |
How are records added to serial files? Where is new data added to(appended)? | Data is stored in the order that it arrives. New data is added to the end of the file. |
How are files searched in serial files? Why is this a disadvantage? | The whole file is searched from the beginning until the correct record is located. There are 2 disadvantages: if the file is large then search can take a long time, if the record is not present you will not know until the search is finished. |
How are records deleted in serial and sequential files? | Removing a record leaves a gap in the file. This means that when a file is deleted the entire file is copied to a new file without the records that will be deleted. |
What is the definition of sequential files? | A collection of records stored one after each other in key sequence. |
How are records added to sequential files? | A new record is inserted within the existing records. A new file is created and all the records are copied until the new one can be inserted into it's proper place. |
How are records searched in sequential files? | Files are searched from the beginning until the record is found. However if you reach a key field that is higher than the one you are searching for then the search ends as it knows the record is not present. |
What are indexed sequential files ? | Where records are stored using a key field, however an index is also stored which allows the records to be accessed directly |
What is the other name for direct access files? | Random access files |
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