Question

I am trying to replace a Table (FooTable) in my DataSource (an SQL CE Database) by a DataTable (which bind to a DataGrid). The reason I want to do this is: after I populate from a Database to a DataSet (which show all the rows on the DataGrid), I might edit, delete, and add multiple rows to the DataTable. Instead of updating my changes to DataSource (SQL CE) each time I modified the DataTable, I want to do it collectively at the end of the session.

My approach is straight-forward:

1. `DELETE` all data from my DataSource table (FooTable) (I’m using **SQL CE**, so `TRUNCATE` is not available)
2. INSERT the `DataTable’s` data in to the emptied DataSource Table

Following is my C# code

/* Truncate the DataSource Table */
SqlCeCommand delCmd = new SqlCeCommand("DELETE FROM FooTable", conn)
conn.Open();
delCmd.ExecuteNonQuery();
conn.Close();

/* Insert DataTable into an empty DataSource Table */
string ins = @"INSERT INTO FooTable (FooName) values (@fooName)";
SqlCeCommand cmd = new SqlCeCommand(ins, conn);
da.InsertCommand = cmd;
da.Update(ds, "FooTable");

The codes work if I add or delete rows on the DataTable, but when I edit a specific row on the DataTable and Insert the table to my DataSource, I get the following error

“Update requires a valid UpdateCommand when passed DataRow collection with modified rows.”

I do not understand why I get this error. I have already empty all rows in my DataSource table and my DataSource shouldn’t not know there are modified rows but insert all DataTable Rows as new rows.

Or, is there a simple way to “REPLACE” a DataSource table by a DataTable?

[EDITED]

I tried setting the RowState manually like below code

foreach (DataRow row in dt.Rows)
{
   row.RowState = DataRowState.Added;
}

but RowState is only read only and cannot be written.

[EDITED – 2nd]
I tried setting it using SetAdded()

foreach (DataRow row in dt.Rows)
{
   row.SetAdded();
}

Then I get the following error:
“SetAdded and SetModified can only be called on DataRows with Unchanged DataRowState.“

Still not manage to get it to work…

[EDITED – 3rd]
So finally get it to work with the following code:

using (SqlCeCommand insCmd = new SqlCeCommand(@"INSERT INTO FooTable (FooName) VALUES (@fooName)", conn))
{
    insCmd.Parameters.Add("@fooName", SqlDbType.NVarChar, 10, "FooName");

    dt.AcceptChanges();
    foreach (DataRow row in dt.Rows)
    {
        row.SetAdded();
    }

    da.InsertCommand = insCmd;
    da.Update(ds, "FooTable");
}

Answer 1

The DataTable tracks RowStates internally.
When you modify an existing row, its RowState becomes Modified, so the DataAdapter tries to run an UPDATE command.

You need to call the SetAdded() method on the modified rows to set their RowStates to Added rather than Modified.