Q: Expressions in DataColumns

[G .Net]

Hi

I've run into a problem when using Expressions in a DataColumn of a
DataTable which I'm updating back to the underlying databas. That is, I'm
loading data into a DataTable in which I've set some of the DataColumns to
calculate their contents using the Expression property.

This all works fine until I try and transfer these calculated values back to
the SQL database. When I try to do this, I get the exception message:

"The column mapping from SourceColumn 'Col 1' failed because the DataColumn
'Col 1' is a computed column"

Is there anyway I can override this exception so the values are written back
to the database?

Geoff

 

[Guest]

You can handle the RowUpdating event and the adapter and copy the value from
the DataRow to the appropriate parameter on the command.

For example,
SqlDataAdapter adapter = ...;
adapter.RowUpdating += delegate(object sender, SqlRowUpdatingEventArgs args)
{
args.Command.Parameters["X"].Value = args.Row["X"];
};
adapter.Update(...);

 

[G .Net]

Hi Mark

I'm afraid I don't follow. Could you explain further?

G

You can handle the RowUpdating event and the adapter and copy the value
from
the DataRow to the appropriate parameter on the command.

For example,
SqlDataAdapter adapter = ...;
adapter.RowUpdating += delegate(object sender, SqlRowUpdatingEventArgs
args)
{
args.Command.Parameters["X"].Value = args.Row["X"];
};
adapter.Update(...);

Hi

I've run into a problem when using Expressions in a DataColumn of a
DataTable which I'm updating back to the underlying databas. That is, I'm
loading data into a DataTable in which I've set some of the DataColumns
to
calculate their contents using the Expression property.

This all works fine until I try and transfer these calculated values back
to
the SQL database. When I try to do this, I get the exception message:

"The column mapping from SourceColumn 'Col 1' failed because the
DataColumn
'Col 1' is a computed column"

Is there anyway I can override this exception so the values are written
back
to the database?

Geoff