BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Deleted records in dBase .DBF files          BorlandTalk.com Forum Index -> Delphi Databases (Desktop) View previous topic :: View next topic   Author Message Neil MacDonald Guest Posted: Wed Feb 07, 2007 11:42 pm    Post subject: Deleted records in dBase .DBF files Can someone say how D2006 and BDE handle deleted records in a .DBF file? I have deleted a record in a TTable in my application, and it disappears from view. It no longer appears when viewing with Database Desktop, and it appears in a 3rd party viewer as a record marked for deletion. All of which I would expect. But if I close my application and restart it, the so-called deleted record shows again. Is there something I should have done to make the deletion stick? Is there an equivalent method to the dBase PACK command to physically delete 'deleted' records, or are they there for all time? Neil Back to top John Herbster Guest Posted: Thu Feb 08, 2007 12:56 am    Post subject: Re: Deleted records in dBase .DBF files "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote Quote: Can someone say how D2006 and BDE handle deleted records in a .DBF file? Neil, Here is "something": As I recall, the first byte in DBF (dBase) table records is reserved for indicating deletion. The DBM (database manager) should change it to the "deleted" state when a record is deleted. I believe that there is a dBase function called "Pack" to compress these deleted records out of the table. Also, if I recall correctly, there was a display filter switch that could turn on and off the display of the "deleted" records (with a special symbol at the left of TDBGrid display of rows which were deleted). Perhaps in your case, the records were not getting written back to the file *or* when reading them back, the filter switch is set to display the "deleted" records. HTH, JohnH Back to top Neil MacDonald Guest Posted: Thu Feb 08, 2007 9:11 am    Post subject: Re: Deleted records in dBase .DBF files John Yes, the DBF file behaves as you say - the 3rd party viewer shows the record is marked as deleted, and I could PACK the file if I had dBase installed. But 1. I can't see how to PACK within Delphi 2. I can't find a property/method for a TTable, TDataSet , TDBGrid which allows deleted records to be displayed or not. Neil "John Herbster" <herb-sci1_at_sbcglobal.net> wrote in message news:45ca20e4$1 (AT) newsgroups (DOT) borland.com... Quote: "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote Can someone say how D2006 and BDE handle deleted records in a .DBF file? Neil, Here is "something": As I recall, the first byte in DBF (dBase) table records is reserved for indicating deletion. The DBM (database manager) should change it to the "deleted" state when a record is deleted. I believe that there is a dBase function called "Pack" to compress these deleted records out of the table. Also, if I recall correctly, there was a display filter switch that could turn on and off the display of the "deleted" records (with a special symbol at the left of TDBGrid display of rows which were deleted). Perhaps in your case, the records were not getting written back to the file *or* when reading them back, the filter switch is set to display the "deleted" records. HTH, JohnH Back to top Andy Vines Guest Posted: Thu Feb 08, 2007 5:14 pm    Post subject: Re: Deleted records in dBase .DBF files "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote in message news:45cada0c (AT) newsgroups (DOT) borland.com... Quote: John Yes, the DBF file behaves as you say - the 3rd party viewer shows the record is marked as deleted, and I could PACK the file if I had dBase installed. But 1. I can't see how to PACK within Delphi 2. I can't find a property/method for a TTable, TDataSet , TDBGrid which allows deleted records to be displayed or not. Neil "John Herbster" <herb-sci1_at_sbcglobal.net> wrote in message news:45ca20e4$1 (AT) newsgroups (DOT) borland.com... "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote Can someone say how D2006 and BDE handle deleted records in a .DBF file? Neil, Here is "something": As I recall, the first byte in DBF (dBase) table records is reserved for indicating deletion. The DBM (database manager) should change it to the "deleted" state when a record is deleted. I believe that there is a dBase function called "Pack" to compress these deleted records out of the table. Also, if I recall correctly, there was a display filter switch that could turn on and off the display of the "deleted" records (with a special symbol at the left of TDBGrid display of rows which were deleted). Perhaps in your case, the records were not getting written back to the file *or* when reading them back, the filter switch is set to display the "deleted" records. HTH, JohnH In the Jedi VCL library there is JvBDEUtils.pas this has ShowDeleted() function and PackTable() and ReIndexTable() funtions. I use the ShowDeleted funtion on my grid then color the deleted fields different to distinguish them. Back to top John Herbster Guest Posted: Thu Feb 08, 2007 5:49 pm    Post subject: Re: Deleted records in dBase .DBF files "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote Quote: I have deleted a record in a TTable in my application, and it disappears from view. It no longer appears when viewing with Database Desktop, and it appears in a 3rd party viewer as a record marked for deletion. ... But if I close my application and restart it, the so-called deleted record shows again. Neil, I found this though I have not read it "Deleted records return alive" http://groups.google.com/group/comp.lang.clipper/browse_frm/thread/fdd3a711e469f732 Can you use your 3-rd party viewer to find *when* the delete flag gets turned off? HTH, JohnH Back to top Neil MacDonald Guest Posted: Thu Feb 08, 2007 9:26 pm    Post subject: Re: Deleted records in dBase .DBF files Thanks, Andy Jedi VCL (including JvBDEUtils.pas)seems a real sledgehammer, which I don't really want to get into - but if I have to, how do you hook the Utils into a TTable, or do you have to use a Jedi version of TTable? Neil "Andy Vines" <andy.vines (AT) amcukfasteners (DOT) co.uk> wrote in message news:45cb0615 (AT) newsgroups (DOT) borland.com... Quote: "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote in message news:45cada0c (AT) newsgroups (DOT) borland.com... John Yes, the DBF file behaves as you say - the 3rd party viewer shows the record is marked as deleted, and I could PACK the file if I had dBase installed. But 1. I can't see how to PACK within Delphi 2. I can't find a property/method for a TTable, TDataSet , TDBGrid which allows deleted records to be displayed or not. Neil "John Herbster" <herb-sci1_at_sbcglobal.net> wrote in message news:45ca20e4$1 (AT) newsgroups (DOT) borland.com... "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote Can someone say how D2006 and BDE handle deleted records in a .DBF file? Neil, Here is "something": As I recall, the first byte in DBF (dBase) table records is reserved for indicating deletion. The DBM (database manager) should change it to the "deleted" state when a record is deleted. I believe that there is a dBase function called "Pack" to compress these deleted records out of the table. Also, if I recall correctly, there was a display filter switch that could turn on and off the display of the "deleted" records (with a special symbol at the left of TDBGrid display of rows which were deleted). Perhaps in your case, the records were not getting written back to the file *or* when reading them back, the filter switch is set to display the "deleted" records. HTH, JohnH In the Jedi VCL library there is JvBDEUtils.pas this has ShowDeleted() function and PackTable() and ReIndexTable() funtions. I use the ShowDeleted funtion on my grid then color the deleted fields different to distinguish them. Back to top Neil MacDonald Guest Posted: Thu Feb 08, 2007 9:29 pm    Post subject: Re: Deleted records in dBase .DBF files Thanks, John That article is about Clipper programming, and as far as I can tell, the dBase end is working OK. The delete flag doesn't get turned off - it's just that Delphi ignores it. Neil "John Herbster" <herb-sci1_AT_sbcglobal.net> wrote in message news:45cb0d4b$1 (AT) newsgroups (DOT) borland.com... Quote: "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote I have deleted a record in a TTable in my application, and it disappears from view. It no longer appears when viewing with Database Desktop, and it appears in a 3rd party viewer as a record marked for deletion. ... But if I close my application and restart it, the so-called deleted record shows again. Neil, I found this though I have not read it "Deleted records return alive" http://groups.google.com/group/comp.lang.clipper/browse_frm/thread/fdd3a711e469f732 Can you use your 3-rd party viewer to find *when* the delete flag gets turned off? HTH, JohnH Back to top Vitali Kalinin Guest Posted: Thu Feb 08, 2007 9:47 pm    Post subject: Re: Deleted records in dBase .DBF files Have you tried old good DbiPackTable? Back to top Neil MacDonald Guest Posted: Fri Feb 09, 2007 12:36 am    Post subject: Re: Deleted records in dBase .DBF files Vitali I didn't know about . I'll give it a try. Many thanks. Neil "Vitali Kalinin" <vitkalinin (AT) yahoo (DOT) com> wrote in message news:45cb45f9$1 (AT) newsgroups (DOT) borland.com... Quote: Have you tried old good DbiPackTable? Back to top Andy Vines Guest Posted: Mon Feb 12, 2007 6:57 pm    Post subject: Re: Deleted records in dBase .DBF files "Neil MacDonald" <neil.mcd (AT) btinternet (DOT) com> wrote in message news:45cb41a2$1 (AT) newsgroups (DOT) borland.com... Quote: Thanks, Andy Jedi VCL (including JvBDEUtils.pas)seems a real sledgehammer, which I don't really want to get into - but if I have to, how do you hook the Utils into a TTable, or do you have to use a Jedi version of TTable? Neil You don't need to use the full JVCL, just include the JvBDEUtils in the unit and then you just feed it your standard TTable. eg. 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