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What will cause the error "cannot resolve backlink"?
- Thread starter pctest
- Start date
Basically, every table (.DBF file) that is part of a DBC (database container) has the path to the .DBC file embedded in the .DBF header.
When VFP reports it can't resolve this "backlink", either the table has moved, or the .DBC has moved (or been deleted).
Instead of just moving dbfs around that are in a database, use the "FREE TABLE tablename" command to remove the backlink.
When VFP reports it can't resolve this "backlink", either the table has moved, or the .DBC has moved (or been deleted).
Instead of just moving dbfs around that are in a database, use the "FREE TABLE tablename" command to remove the backlink.
- Thread starter
- #3
Hi wgcs,
I understand that dbf contains the path to the dbc. I'm interested in how to duplicate this error.
I have tried to move a dbf away from its associated dbc and use it. But this will only get the dialogue to "Would you like to try to locate the owning database or delete the link...?
I have tried to delete a dbf and then validate database. This will only yield cannot find the file...
Thank you for any help.
I understand that dbf contains the path to the dbc. I'm interested in how to duplicate this error.
I have tried to move a dbf away from its associated dbc and use it. But this will only get the dialogue to "Would you like to try to locate the owning database or delete the link...?
I have tried to delete a dbf and then validate database. This will only yield cannot find the file...
Thank you for any help.
Try copying a table to a temp location,
drop the table from the DBC,
copy the table back,
then try to open the table.
Without an ON ERROR routine, you get a message "Cannot link table ... with its database.... would you like to try to locate the owning database....", With an ON ERROR, you get
error 1976.
The help says of it:
Cannot resolve backlink (Error 1976)
Visual FoxPro was unable to successfully match a table with its database.
Use VALIDATE DATABASE to verify the links in the database.
drop the table from the DBC,
copy the table back,
then try to open the table.
Without an ON ERROR routine, you get a message "Cannot link table ... with its database.... would you like to try to locate the owning database....", With an ON ERROR, you get
error 1976.
The help says of it:
Cannot resolve backlink (Error 1976)
Visual FoxPro was unable to successfully match a table with its database.
Use VALIDATE DATABASE to verify the links in the database.
- Thread starter
- #5
Mike Lewis
Programmer
Wgcs,
Instead of just moving dbfs around that are in a database, use the "FREE TABLE tablename" command to remove the backlink.
Just to clarify -- for the benefit of anyone not familiar with this area: FREE TABLE should only be used to resolve the sort of problem that Pctest mentioned. Don't use it merely to remove a table from a database, for which you should use REMOVE TABLE instead.
Even with REMOVE TABLE, you will lose all the validation rules, triggers, default values, long field names and other DBC-based information held for the table.
Mike
Mike Lewis
Edinburgh, Scotland
My Visual Foxpro web site: My Crystal Reports web site:
Instead of just moving dbfs around that are in a database, use the "FREE TABLE tablename" command to remove the backlink.
Just to clarify -- for the benefit of anyone not familiar with this area: FREE TABLE should only be used to resolve the sort of problem that Pctest mentioned. Don't use it merely to remove a table from a database, for which you should use REMOVE TABLE instead.
Even with REMOVE TABLE, you will lose all the validation rules, triggers, default values, long field names and other DBC-based information held for the table.
Mike
Mike Lewis
Edinburgh, Scotland
My Visual Foxpro web site: My Crystal Reports web site:
Mike Lewis
Programmer
Mike,
Good point about DROP TABLE. If I remember right, you don't get the warning even if you have SET SAFETY ON.
Mike
Mike Lewis
Edinburgh, Scotland
My Visual Foxpro web site: My Crystal Reports web site:
Good point about DROP TABLE. If I remember right, you don't get the warning even if you have SET SAFETY ON.
Mike
Mike Lewis
Edinburgh, Scotland
My Visual Foxpro web site: My Crystal Reports web site:
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