| File Access | ||
| When records in a file need to be accessed there are two
ways of doing it....
|
||
| Serial Access
This means ...start at the beginning of the file and access each record in turn until the one needed is found.
|
If files are stored on magnetic tape then serial access is the only method of access. | |
| Direct Access
The computer can calculate (from the key field) where the record is stored in the file, and can then access the record directly from that position. Direct access of records will generally be much faster than serial access.
|
Direct access can only be
used if files are stored on media such as disk, CD, DVD...
Direct access is also known as random access |
|
| Exercise : File Access | ||
|
of records involves accessing each record in turn.
is used if the computer can calculate where a record is stored and directly accesses only that record. Applications which need fast access to data will need to use |
||
| (Green indicates success) | ||