Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

                                                 ◄Contents►  ◄Index►  ◄Back►
─────────────────────────────────────────────────────────────────────────────
                           ◄Knowledge Base Contents►  ◄Knowledge Base Index►
 
 How to Remember Current ISAM Record for Different Indexes - Q79149
 
 Method 3
 --------
 
 In some situations, you may want to know the physical position of a
 record within an index. This position could be used to display the
 relative position of the current record to the user of the database
 application, giving them an indication of "where they are" in their
 database file. Knowing the record's position also allows you to easily
 return to that record when indexes are changed. To do this, keep a
 position element in the type used to create the table as in the
 example below:
 
 TYPE DataType
 LastName AS STRING * 15
 PhoneNumber AS STRING * 12
 RecordPosition AS INTEGER  ' Keeps track of record's position in index.
 END TYPE
 
 DIM Temp AS DataType
 
 OPEN "test.mdb" FOR ISAM DataType "tabletype" AS #1
 
 ' Miscellaneous code goes here that would insert records into table,
 ' leaving the RecordPosition element empty (zero).
 
 CREATEINDEX #1, "One", 0, "LastName"
 SETINDEX #1, "One"      ' Forces first record to be current record.
 count = 0
 WHILE NOT EOF(1)
  count = count + 1      ' Mark first record with a one, etc.
  RETRIEVE #1, Temp
  Temp.RecordPosition = count
  UPDATE #1, Temp
  MOVENEXT #1
 WEND
 ...
 
 The element Temp.RecordPosition can be used as a marker in correlation
 with the second part of Method 1 (for example, Index1Pos =
 Temp.RecordPosition). Index1Pos can be used to count to the record
 that was current when the index was last used. Also, any time a
 RETRIEVE is done with index "One", the associated record number can be
 displayed (for example, LOCATE 25, 77: PRINT Temp.RecordPosition).
 Note that the RecordPosition field of records would have to be updated
 any time records are INSERTed, UPDATEd or DELETEed, because these
 operations could change the order of the records in the index.