SCAN INDEX

version 3

SCAN INDEX (aField; number{; > or <})

SCAN INDEX returns a selection of number records from the table containing the aField field. If you pass <, SCAN INDEX returns the number of records from the end of the index (high values). If you pass >, SCAN INDEX returns the number of records from the beginning of the index (low values). This command is very efficient because it uses the index to perform the operation.

Note: The selection obtained is not sorted.

SCAN INDEX only works on indexed fields. This command changes the current selection of the table for the current process and loads the first record of the selection as the current record.

If you specify more records than exist in the table, SCAN INDEX will return all the records.

The following example mails letters to 50 of the worst customers and then to 50 of the best customers:

   SCAN INDEX([Customers]TotalDue;50;<)  ` Get the 50 worst customers 
   ORDER BY([Customers]Zipcode;>)  ` Sort by Zip codes 
   OUTPUT FORM([Customers];"ThreateningMail") 
   PRINT SELECTION([Customers])  ` Print the letters
   SCAN INDEX([Customers]TotalDue;50;>)  ` Get the 50 best customers 
   ORDER BY([Customers]Zipcode;>)  ` Sort by Zip codes 
   OUTPUT FORM([Customers];"Thanks Letter") 
   PRINT SELECTION([Customers])  ` Print the letters

ORDER BY, QUERY, REDUCE SELECTION.