: an exception raised

[Guest]

Hello,

Dim row As DataRow
Dim column As DataColumn
For Each row In myDTSrc.Rows
For Each column In myDTSrc.Columns
myRowDest(column.ColumnName.ToString) =
row(column.ColumnName.ToString)
Next
myDTDest.Rows.Add(myRowDest)
myDA.Update(myDTDest)
myDTDest.AcceptChanges()
Next

This code adds first row from MyDTSrc to myDTDest which is attached an SQL
table, but at the second row I get exception "This row already belongs to
this table", what is problem?
Thanks,
Jim.

 

[jlien]

Try this:

Dim row As DataRow
Dim column As DataColumn
For Each row In myDTSrc.Rows
myRowDest = myDTDest.NewRow
For Each column In myDTSrc.Columns
myRowDest(column.ColumnName.ToString) =
row(column.ColumnName.ToString)
Next
myDTDest.Rows.Add(myRowDest)

Next
myDA.Update(myDTDest)
myDTDest.AcceptChanges()

 

[Karl Seguin]

Jim,
The error pretty clearly states what the problem is. A datarow can only
belong to 1 datatable....remember all these are references so all you are
copying is the reference to the same datarow...

Why not just do:

myDtDest = myDtSrc.Copy(); ??

Karl

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[Eliyahu Goldin]

Jim,

You need to create new myRowDest in every loop.

Eliyahu

 

[Guest]

Thanks Karl, I did,
myDTDest = myDTSrc.Copy()
myDA.Update(myDTDest)
but I do nto see data in table. What might be the problem?

 

[Guest]

Thanks Eliyahu,
I did this, and I am wondering if this will cause any overflow problem
because of a new decleration for each row. It might be a big table.

Dim row As DataRow
Dim column As DataColumn
For Each row In myDTSrc.Rows

Dim myRowDest As DataRow = myDTDest.NewRow

For Each column In myDTSrc.Columns
myRowDest(column.ColumnName.ToString) => row(column.ColumnName.ToString)
Next
myDTDest.Rows.Add(myRowDest)
myDA.Update(myDTDest)
myDTDest.AcceptChanges()
Next

 

[Eliyahu Goldin]

This is how it HAS to be. Every row HAS to be a separate object.

Eliyahu

 

[Guest]

I am new in asp.net, so if there is 5000 object is created in that function,
will it cause any problem? I assume the object life will end when the
function ends.

 

[Eliyahu Goldin]

It should not be any different from reading 5000 rows from a database.When
you read 5000 rows from a database, every row is represented by a separate
object. When you change one row, you wouldn't like another row to get the
same changes would you? I am not aware of any special limitation for tables.
Usual memory limitations apply. 5000 rows is not a very large table, should
be ok. Depends on row content of course.

Since you attach row objects to a table and the table persists outside the
function, the row objects will persist too.

Eliyahu

 

[Guest]

I think there has to be a better way than copying each COLUMN BY COLUMN

TNX
Hitesh