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Tip of the Day
Language: Visual FoxPro
Expertise: Beginner
Jan 21, 2000

Deleting a Record

Question:
I am currently building a VB application that needs to delete records in a .dbf field. The connection to the database is established through ADO by using a DSN. Currently, when I attempt to delete a record (using SQL's delete), the record is simply marked to be deleted, but is not deleted.

How do I delete the record?

Answer:
Visual FoxPro has a command called PACK that removes records marked as "deleted" from the DBF and rebuilds the indices on the table. It requires exclusive use of the table.

There are two approaches for calling this command. First, you could create a VFP COM object that has a method called Pack with a parameter of what file (with full path) to pack. You could then instantiate this object from your application and call the Pack method.

Create a project with the following program and compile it as a DLL:

 
DEFINE CLASS VFPDBFUtility AS CUSTOM OLEPUBLIC
PROC Pack
LPARAMETERS tcTableFile

   LOCAL llError
   llError =.F.
   ON ERROR llError=.T.
   USE (tcTableName) EXCLUSIVE
   IF llError
      RETURN .F.
   ENDIF
   PACK
   USE
   ON ERROR

   *-- Return .T. if no error, .F. if error occurred
   RETURN !llError

ENDPROC
ENDDEFINE
 
The other approach would be to instantiate VFP as an automation server and use the DoCmd method to run the commands. This requires that VFP is installed on the server:
 
lcFile = 'C:\mydbf.dbf'
oVFP = CREATEOBJECT('visualfoxpro.application')
oVFP.DoCmd('USE '&& lcFile &&' EXCLUSIVE')
oVFP.DoCmd('PACK')
oVFP.DoCmd('USE')
 
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