PRB: Table/dbf File Record Count Incorrect Based on File Size (263902)

RESOLUTION

In most cases, the preceding symptoms can be overcome by modifying the header of the table/dbf file to reflect a calculated number of records. This process is offered as a workaround. Its usefulness is limited to a situation where all of the following are true:

• The expected data is contained within the file.
• The file size is consistent with the amount of data that it contains.
• The file's Header Information, apart from the bytes that store the number of records, is all valid.

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact a Microsoft Certified Partner or the Microsoft fee-based consulting line at (800) 936-5200. For more information about Microsoft Certified Partners, please visit the following Microsoft Web site: For more information about the support options that are available and about how to contact Microsoft, visit the following Microsoft Web site: The following demonstrates how to calculate the number of records that a table should contain.

1. Create a program named RECCALC.PRG and add the following code:

   IF EMPTY(ALIAS())
      =MESSAGEBOX("No table is open in the selected work area.")
      RETURN
   ENDIF
   lnFile = ADIR(laFile,DBF())
   IF lnFile > 0
      lnFileSize = laFile(2)
      lnRecords = INT((lnFileSize - HEADER())/RECSIZE())
   ELSE
      lnRecords = RECCOUNT()
   ENDIF
   RETURN lnRecords
   					

2. Open a table in the currently selected work area.
3. To show the calculated number of records printed to the Visual FoxPro screen, run the program from the Command window as follows:

   ?RECCALC()
   					

In the event that the table header has been written or modified to reflect that the table contains any number of records different from what is actually contained in the file, the following code can be used to modify the header to reflect the calculated number of records. This program uses low-level file input/output (I/O) to modify the table header programmatically.

1. Create a program named RECHEADR.PRG and add the following code:

   IF EMPTY(ALIAS())
      =MESSAGEBOX("No table is open in the selected work area.")
      RETURN
   ENDIF
   
   lnCalcRecords = RECCALC()
   
   IF RECCOUNT() <> lnCalcRecords
      lcFileName = DBF()
      USE
      lnHandle = FOPEN(lcFileName, 2)
   
      IF lnHandle > 0
         lnHeaderData = FREAD(lnHandle,32)
         BKUP_lnHeaderData = lnHeaderData
   
         lnHeaderByte8 = CHR(INT(lnCalcRecords / (256^3)))
         lnHeaderByte7 = CHR(INT(lnCalcRecords / (256^2)))
   
         lnHeaderByte6 = CHR(INT(lnCalcRecords / 256) - ;
            IIF(lnCalcRecords / 256 > 256, ;
                (INT(INT(lnCalcRecords / 256) / 256) * 256), ;
                0))
   
         lnHeaderByte5 = CHR(MOD(lnCalcRecords,256))
   
         lnHeaderData = SUBSTR(lnHeaderData, 1, 4) + ;
            lnHeaderByte5 + lnHeaderByte6 + lnHeaderByte7 + ;
            lnHeaderByte8 + SUBSTR(lnHeaderData, 9)
   
         =FSEEK(lnHandle, 0)
         =FWRITE(lnHandle, lnHeaderData)
         =FCLOSE(lnHandle)
      ENDIF
      USE (lcFileName)
      RETURN .T.  && Program modified the table header
   ELSE
      RETURN .F.  && Program did not modify the table header
   ENDIF
   					

2. Open a table in the currently selected work area.
3. To modify the table header to reflect the calculated number of records, run the program from the Command window as follows:

   ?RECHEADR()
   					

4. If a modification was made, note that a logical '.T.' (True) is printed to the Visual FoxPro screen. Otherwise, a logical '.F.' (False) is printed.