Re: MI Accessing MapInfo data table from DLL

[Geograf�a y Electr�nica.]

Dear Thomas:

The only way I've found to open dbf tables from mapinfo and from other
applications at the same time is with odbc.  MapInfo cannot open/read the
table if it's open (even shared/readonly) by other application.  When you
open a table as "shared" in, say, foxpro, it can be shared by other
fox/dbase/clipper/odbc applications, but locked out from MapInfo's direct
access. (Troy: Want an option? Try opening it with Excel).  Newest 5.0
"live link" is good for small tables,  and "download copy" is better for
large tables, just remember to "refresh" it often.  

But if you try to pass values between applications, why not try DDE?   Two
tables with a common field (can be done with the "create table" syntax
present in any StreetInfo .tab table)  are troublesome since you have to
control that every record in a table matches one and only one record in the
other, among other problems.  

By the way, if you are are planning to make a dbf table mappable, view
objects from within mapinfo and edit the dbf externally, just remember that
inserting or deleting/packing the dbf will destroy the mapinfo .id
relations between the .dbf table and the .map table, ruining completely
your table, and without a MapInfo warning.


At 01:01 AM 12/04/99 +0200, you wrote:
>Dear Lists,
>
>For data entry I have developed a function in a Delphi DLL, which opens a
>form, through which the user should enter attribute data for MapInfo
>objects. It seemed not possible to access the MapInfo table from the DLL
>while the table (DBF Format) is open in MapInfo. Does MapInfo open dbf-files
>only for exclusive use ? How can I realise shared access to a MapInfo dBase
>file, when it is opened in MI ? Is it necessary to use ODBC connections ?
>
>In order to develop data entry forms visually, I am testing the possibilites
>of using external Delphi DLLs. What approaches other than MapX have MapBasic
>developers used to include external forms for data entry in their MapBasic
>applications ?
>
>I have chosen the approach of placing most of the attribute tables into a
>second dbf table so that the table containing the map objects and the
>attribute table are linked through a common field. The result is, however,
>that some fields are not directly available for thematic shading anymore,
>since I want to keep the second attribute table closed, so that it is
>accessible from the external forms.
>
>I hope I have been clear enough to specify the problems. MapX is not an
>option, because the client wants to have a MapBasic application working from
>within MapInfo.
>
>TIA
>
>
>Thomas G�lden
>Diplom-Geologe
>
>Email (privat):      [EMAIL PROTECTED]
>Email (dienstl.):   [EMAIL PROTECTED]
>
>
>
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---------------------------------
   Ing. Juan Pufleau Correa
Geograf�a y Electr�nica, SA de CV
        Aguascalientes
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