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ADO corrupts date time values in where clause

Posted on 2006-11-16
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Last Modified: 2008-01-09
We have a propreitary application similar to VB that uses ADO for talking to an Oracle database. We use ORaoledb.oracle as the provider.

At times we are getting error messages like "Row cannot be located for updating" and sometimes ORA-01841 Invalid date.

This error does not happen to all the users. But once it starts occuring for a user, it's persistent till the time user logs out and logs back into the application.

We were able to do an oracle trace and identify the sql statements that were causing this.

In some cases we see that the year component of a date field in the where clause being chopped off. This happens only in fields where date is 30-DEC-1899.
(ie) instead of passing 1899-12-30 09:30:00 it passes -12-30 09:30:00. This throws the invalid date format error.

Also in some cases the time component seems to be offset by 10 secs (ie) In the database if the time component of a date field is 00:00:00, ado passes 00:00:10 in the where clause. Thus causing the unable to locate row error.

Now all these are in the where clause.Since the where clause is something that ADO builds, we are at a loss as to what's going on.

The values for the same fields (used in the set protion of the update) passed from the application are in correct format.

Any ideas or thoughts welcome.
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Question by:sathyagiri
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by:sathyagiri
ID: 17960788
Also is there a way to trace the ADO calls?
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Expert Comment

by:Shiju Sasidharan
ID: 17964262
What is the data type of that table field?

Also try to post the portion of your code where you actually build the where clause
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by:sathyagiri
ID: 17965079
The application does not build the where clause. We just select a record and modify the values and call ADO UPDATE.

ADO seems to be generating the where clause with all the columns in the table.
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Expert Comment

by:Shiju Sasidharan
ID: 17977069
>>The application does not build the where clause
Please provide the SQL code segment you are using. This will be helpful for us to debug
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Author Comment

by:sathyagiri
ID: 17979145
Here's what we do

ADO select * from table where <condition>

ADO FINDFIRST <table>

-- Set new values here
ADO UPDATE <context> ALL

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RainUK earned 500 total points
ID: 17986148
"Row cannot be located for updating"  - The error you are getting usually comes from when you select a set of rows and whilst you are reading and modifying them in your version of the cursor, somebody else makes an update to the rows you have selected.

Hence when you go to update them you get the error that the rows cannot be found for updating.

Basically the (Row Version) property in ADO has changed since you last read the rows because somebody else has updated or deleted the rows in the DB.

As for the date thing, not sure what your code does to update the date, but you can format the date in either VB6 or T-SQL into a certain format before updating it.
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by:Shiju Sasidharan
ID: 17993227
>>ADO UPDATE <context> ALL

simply seeing the algorithm we can not predict the exact error.
Please try to post the exact source code segment for the same
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