Question

I am trying to delete the data present in the dataset with following code:

stateflowDataSet dsobject = new stateflowDataSet();
stateflowDataSetTableAdapters.dbo_statetableTableAdapter statetableadapter = new         stateflowDataSetTableAdapters.dbo_statetableTableAdapter();
statetableadapter.Fill(dsobject.dbo_statetable);
dsobject.dbo_statetable.Clear();
statetableadapter.Update(dsobject);

But after this line when use statetableadapter.Fill(dsobject.dbo_statetable); the data is still retained.

Is the way in which I am clearing the data right?

Is there any other problem with the code?

Answer 1

Removing DataRows from a DataTable does not mean that you’ll delete them from your DBMS. The opposite is true, actually you’re preventing them from being deleted even if you would have called DataRow.Delete() before.

The reason is: only DataRows that belong to a DataTable can be deleted by

DataAdapter.Update(table)

This will delete every row in the table with DataRowState=Deleted.
Therefor you need to use the Delete method.

foreach(DataRow row in dsobject.dbo_statetable.Rows)
{
    row.Delete();
}
statetableadapter.Update(dsobject.dbo_statetable);

You could do it also in one batch which would be more efficient, therefor you need to set the DataAdapter’s UpdateBatchSize to 0(unlimited).

Another way would to delete all rows is to use a simple SqlCommand with CommandText DELETE FROM Table:

using(var con = new SqlConnection(ConfigurationSettings.AppSettings["con"]))
using(var cmd = new SqlCommand())
{
    cmd.CommandText = "DELETE FROM Table";
    cmd.Connection = con;
    con.Open();
    int numberDeleted = cmd.ExecuteNonQuery();  // all rows deleted
}

Now you need to remove(not delete, what is the core of your question) the rows from the DataTable manually since you’ve also deleted them manually in the database:

dsobject.dbo_statetable.Clear();