Re: Pb with linked tables on PG8

From: Zlatko Matić <zlatko(dot)matic1(at)sb(dot)t-com(dot)hr>
To: "jeremy `" <norman1nz(at)hotmail(dot)com>, <ets(at)rolland-fr(dot)com>, <pgsql-general(at)postgresql(dot)org>
Subject: Re: Pb with linked tables on PG8
Date: 2005-06-13 12:41:37
Message-ID: 000101c57067$f7fea3d0$45221dc3@zlatkovyfkpgz6
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Hi.
I'm forwarding you what I answered to Rolland about it. This "#deleted"
phenomena is something often, but can be easily solved.
It seems to be common problem with Access connectiong to ODBC data source.
Access has some problems to determine primary key...
You should not use textual fields as primary key. Insted, add some bigserial
(integer autoincrement field) into your tables and make such field primary
key. Then relink your tables. This will solve your problem. Also, it is good
to add timestamp field into tables.
Also, be aware that your tables names should not be too long, because if
they are long you will have problems with relinking. Access would not relink
correctly (preassuming that you will use DSN-less and relinking on each
startup).

Bye.

Zlatko

For your information, this is explanation from MSDN:
"
ACC: "#Deleted" Errors with Linked ODBC Tables
View products that this article applies to.
Article ID : 128809
Last Review : May 6, 2003
Revision : 1.0

This article was previously published under Q128809
On this page
SYMPTOMS
CAUSE
RESOLUTION
MORE INFORMATION
Steps to Reproduce Behavior
APPLIES TO

SYMPTOMS
When you retrieve, insert, or update records in a linked ODBC table, each
field in a record contains the "#Deleted" error message. When you retrieve,
insert, or update records using code, you receive the error message "Record
is deleted."
Back to the top

CAUSE
The Microsoft Jet database engine is designed around a keyset-driven model.
This means that data is retrieved, inserted, and updated based on key values
(in the case of a linked ODBC table, the unique index of a table).

After Microsoft Access performs an insert or an update of a linked ODBC
table, it uses a Where criteria to select the record again to verify the
insert or update. The Where criteria is based on the unique index. Although
numerous factors can cause the select not to return any records, most often
the cause is that the key value Microsoft Access has cached is not the same
as the actual key value on the ODBC table. Other possible causes are as
follows:
. Having an update or insert trigger on the table, modifying the key
value.
. Basing the unique index on a float value.
. Using a fixed-length text field that may be padded on the server
with the correct amount of spaces.
. Having a linked ODBC table containing Null values in any of the
fields making up the unique index.
These factors do not directly cause the "#Deleted" error message. Instead,
they cause Microsoft Access to go to the next step in maintaining the key
values, which is to select the record again, this time with the criteria
based on all the other fields in the record. If this step returns more than
one record, Microsoft Access returns the "#Deleted" message because it does
not have a reliable key value to work with. If you close and re-open the
table or choose Show All Records from the Records menu, the "#Deleted"
errors are removed.

Microsoft Access uses a similar process to retrieve records from an linked
ODBC table. First, it retrieves the key values and then the rest of the
fields that match the key values. If Microsoft Access is not able to find
that value again when it tries to find the rest of the record, it assumes
that the record is deleted.
Back to the top

RESOLUTION
The following are some strategies that you can use to avoid this behavior:
. Avoid entering records that are exactly the same except for the
unique index.
. Avoid an update that triggers updates of both the unique index and
another field.
. Do not use a Float field as a unique index or as part of a unique
index because of the inherent rounding problems of this data type.
. Do all the updates and inserts by using SQL pass-through queries so
that you know exactly what is sent to the ODBC data source.
. Retrieve records with an SQL pass-through query. An SQL pass-through
query is not updateable, and therefore does not cause "#Delete" errors.
. Avoid storing Null values within any field making up the unique
index of your linked ODBC table.

Back to the top

MORE INFORMATION
Note: In Microsoft Access 2.0, linked tables were called attached tables.
Steps to Reproduce Behavior

1. Open the sample database Northwind.mdb (or NWIND.MDB. in Microsoft
Access 2.0)
2. Use the Upsizing Tools to upsize the Shippers table.

NOTE: This table contains an AutoNumber field (or Counter field in
Microsoft Access 2.0) that is translated on SQL Server by the Upsizing Tools
into a trigger that emulates a counter.
3. Open the linked Shippers table and enter a new record. Make sure
that the record you enter has the same data in the Company Name field as the
previous record.
4. Press TAB to move to a new record. Note that the "#Deleted" error
fills the record you entered.
5. Close and re-open the table. Note that the record is correct.
"
----- Original Message -----
From: "jeremy `" <norman1nz(at)hotmail(dot)com>
To: <ets(at)rolland-fr(dot)com>; <pgsql-general(at)postgresql(dot)org>
Sent: Monday, June 13, 2005 1:23 AM
Subject: Re: [GENERAL] Pb with linked tables on PG8

>i had the exact same thing using the same scenario but with pg 8.0.3
>installed on the same win XP pro machine.
> The strange thing is when I closed the table and opened it again, all the
> fields containing #deleted then showed up with the values I actually
> input.
> So i'm thinking theres some bug in refreshing the table each time you
> enter a new record.
>
>>From: "Ets ROLLAND" <ets(at)rolland-fr(dot)com>
>>Reply-To: "Ets ROLLAND" <ets(at)rolland-fr(dot)com>
>>To: <pgsql-general(at)postgresql(dot)org>
>>Subject: [GENERAL] Pb with linked tables on PG8
>>Date: Thu, 9 Jun 2005 13:19:57 +0200
>>
>>Hello !
>>
>>I have an Access database using linked tables on PG 8.0.3 (on Windows 2003
>>server).
>>I use pgODBC 8.00.01.01.
>>Some tables appear like deleted !
>>In Access I see :
>>Categ : Table
>>vt_cat vt_libcat
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>#Supprimé #Supprimé
>>(Supprmé means deleted in French)
>>I try to delete the link and recreate it, same problem !
>>I try a VACUUM FULL ANALYSE on the database, same problem !
>>How can I solve this problem ? Why ?
>>Many thanks for all your explainations.
>>Regards.
>>
>>Luc
>
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