How to Remove Records from a Table Without Using Delete/Pack

MORE INFORMATION

Step-by-Step Procedure

1. Open a program file, name it Lowlevel.prg, and type the following function code:

      FUNCTION ZAPLAST
      PARAMETER lnY
      IF USED()
        lnZ=RECCOUNT()
        IF lnY<=lnZ
          lcFILENAME=DBF()
          USE
          lnHANDLE=FOPEN(lcFILENAME,2)
          IF lnHANDLE>0
            lcBYTE=FREAD(lnHANDLE,32)
            lnFLD_SIZE=ASC(SUBSTR(lcBYTE,11,1))+;
               (ASC(SUBSTR(lcBYTE,12,1))*256)
            lnFILESIZE=FSEEK(lnHANDLE,0,2)
            lnX=lnZ-lnY
            lcBYTE8=CHR(INT(lnX/(256*256*256)))
            lcBYTE7=CHR(INT(lnX/(256*256)))
            lcBYTE6=CHR(INT(lnX/256))
            lcBYTE5=CHR(MOD(lnX,256))
            lcBYTE=SUBSTR(lcBYTE,1,4)+lcBYTE5+;
               lcBYTE6+lcBYTE7+lcBYTE8+SUBSTR(lcBYTE,9)
            =FSEEK(lnHANDLE,0)
            =FWRITE(lnHANDLE,lcBYTE)
            =FCHSIZE(lnHANDLE,lnFILESIZE+(lnFLD_SIZE*lnX))
            =FCLOSE(lnHANDLE)
          ENDIF
          USE &lcFILENAME
        ENDIF
      ENDIF
   							

2. Save and close Lowlevel.prg
3. Test the function by removing a single record from a table. For this example, use the Customer.dbf table - but back up the table first. Records that are deleted with ZAPLAST() cannot be recovered.
   1. In the Command window, type:

            SET PROCEDURE TO LOWLEVEL.PRG
            USE C:\FPW26\TUTORIAL\CUSTOMER EXCLUSIVE
      								

   2. Take note of how many records are in the table. For this example, there are 500 records.
   3. In the Command window, type:

            =ZAPLAST(1)
      								

   4. Note that there is one less record in the database. Originally there were 500 records; now there are only 499.
4. Any number of records can be deleted. For example, to delete 27 records, change step 3.c. to =ZAPLAST(27)