adding rows from one datatable to another

[Sam]

Hi,
The following code :


For Each r As DataRow In dtFlow.Rows
Dim arow As DataRow = dtAllFlows.NewR ow
arow = r
dtAllFlows.Rows .Add(arow)
Next

leads to the error 'This row already belongs to another table '
at the line dtAllFlows.Rows .Add(arow).
I guess I should just do dtAllFlows = dtFlow.copy, but I can't as the
code above is contained in a For loop and at each iteration, I add new
rows (dtFlow changes at each iteration).

How can I solve this problem ?

Regards

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam,

I assume that this is what you want to do

importrow

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatadatatableclassimportrowtopic.asp

I hope this helps,

Cor

[Sam]

Re: adding rows from one datatable to another

Thanks Cor ;-)

[Sam]

Re: adding rows from one datatable to another

Actually, I might have spoken too quickly.

For Each r As DataRow In dtFlow.Rows
Dim arow As DataRow = dtAllFlows.NewR ow
arow = r
dtAllFlows.Impo rtRow(arow)
Next

It looked right but in fact when I try to access the data:

dtallflows.Rows (0).Item(0)

gives :

Run-time exception thrown : System.IndexOut OfRangeExceptio n - Cannot
find column 0.

What's going on ?

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam

When you try to copy a complete table, than you can use table.copy

However this is a sample from me how to sort a datatable, you see than the
use of the import in it.

\\\
Dim dv As New DataView(dt)
dv.Sort = "bla"
Dim dtnew As DataTable = dt.Clone
For Each dvr As DataRowView In dv
dtnew.ImportRow (dvr.Row)
Next
///

I hope this helps,

Cor

[Sam]

Re: adding rows from one datatable to another

As I said in the first thread, I don't want to do a copy as I add the
rows in a for loop (concatenate if you prefer). therefore I have to use
ImportRow, which leads to the error mentionned in my second thread...
Can you help further ?

Thx

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam,.

The only thing you can do is copy it, use an extra dataview, remove it from
the first.

However you cannot have a reference in one datarow to two tables.

There is this property in the datarow that should explain that to you if my
text did not.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatadatarowclasstabletopic.asp

It is a litte bit difficult to set one address to two tables.

I hope this helps,

Cor

[Sam]

Re: adding rows from one datatable to another

Ok, I do that now :

Dim dvTmp As new DataView
dvTmp.Table = dtFlow
dtFlow = Nothing
For Each r As DataRowView In dvTmp
dtAllFlows.Rows .Add(DirectCast (r, DataRow))
Next

But the Add line doesn't work ( invalid cast ). How can I add a
datarowview to a datatable ??

Thx

[Sam]

Re: adding rows from one datatable to another

This should be correct I guess...

dtAllFlows.Rows .Add(r.Row)

But I keep getting the error ; the datarow already exists in another
table :(
How come ??

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam,

Did you read my message?

How you want to do this

myproperty a = adress of datatable wherein it is connected
datarow.a = table1
datarow.a = both table1 and table2

Cor

[Sam]

Re: adding rows from one datatable to another

Cor,
I read your message but :

1. the link u gave me does not work
2. I don't understand this sentence :

The only thing you can do is copy it, use an extra dataview, remove it
from
the first.

Could you explain that to me if you don't mind please ?

Thx

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam,

Again.

You cannot add a reference from a datarow to 2 datatables. (That is what you
do with Add or insertAt)

Therefore is the only thing that you can do.
Create a copy from the original and add that to your new table
Remove the reference from the first and than add it to the new table
Create an extra dataview instead of that extra table.

The copy you have already, the second seems for me out of sense and the
thirth is probably what you need.

dim dv as new dataview(mydata table)

In fact you have now a complete view on your table. If you want only some
rows than you need a rowfilter

dv.rowfilter = "City = 'Amsterdam'"

I hope this helps

Cor

[Sam]

Re: adding rows from one datatable to another

I'm very very confused. Sorry :(
Are you actually saying I should do that :

1. Create a copy from the original and add that to your new table
dim dtAllFlows as datatable
dtAllFlows = dtFlow.copy

2.Remove the reference from the first and than add it to the new table
???? what does this mean ?

3. Create an extra dataview instead of that extra table.
What for ? :
Dim dvTmp As new DataView
dvTmp.Table = dtFlow

Could you give a very simple example please, as I really don't
understand the above ?
Sorry for bothering :(
Thx

[Cor Ligthert]

Re: adding rows from one datatable to another

Sam,

I am only saying that you cannot have the same datarow in 2 datatables.

However you only tell that you want this and I only try to explain you why
this is impossible.

Cor

[Sam]

Re: adding rows from one datatable to another

I understood this. But you've also tried to explain a work around and I
dont understand it !

You said :
Therefore is the only thing that you can do.
Create a copy from the original and add that to your new table
Remove the reference from the first and than add it to the new table
Create an extra dataview instead of that extra table.


Could you give a little example of this (just a few lines of code) as I
can't get it.

Thx a lot