How to override values in merging DataTables using .Merge() method?

Question

Is there a way to override values in merging DataTables using .Merge() method?

For example if I have two DataTables with the same schematics.

Both have two Columns: Names | Enabled;

DataTable1 first row entries are: Peter Punani | true;

DataTable2 first row entries are: Peter Punani | false;

If I merge them using .Merge() method - DataTable1.merge(DataTable2); -, DataTable1 will then have 2 rows and look like this:

Names | Enabled;  
Peter Punani | true;  
Peter Punani | false;

Now obviously if I try to .Update() that using SqlCommandBuilder to my SQL DB it will give me an error statement, because of two identical values in my Primary Key(Names).

But I want DB1 to accept the differences from DB2, so it would look like: (and do that with all other entries that differ from DB1.)

Names | Enabled;  
Peter Punani | false;

So what is the best way to merge these tables, so I can update them properly?

score 0 · Accepted Answer · answered Mar 26 '15 at 15:42

I just implemented my method this way now:

public static bool synchSqlData(DataTable UpdateTable, string selectedTableName, SqlConnection sqlCon, DataTable MergeTable, bool merge)
    {
        bool success = false;
        //Mitgabe eines SELECT cmds für SqlCommandBuilder zum generieren von INSERT,DELETE und UPDATE
        using (SqlCommand sqlCom = new SqlCommand("SELECT * FROM dbo." + selectedTableName, sqlCon))
        {
            SqlDataAdapter da = new SqlDataAdapter(sqlCom);
            SqlCommandBuilder cmb = new SqlCommandBuilder(da);

            da.InsertCommand = cmb.GetInsertCommand();
            da.DeleteCommand = cmb.GetDeleteCommand();
            da.UpdateCommand = cmb.GetUpdateCommand();

            //Zuweisen von PKs
            UpdateTable.PrimaryKey = new DataColumn[] { UpdateTable.Columns[0] };
            MergeTable.PrimaryKey = new DataColumn[] { MergeTable.Columns[0] };

            //Zusammenführen der beiden DataTables in UpdateTable
            if (merge)
            {
                //Setzen der Rows auf changed damit sie bei da.Update() auch erkannt werden ;)
                foreach (DataRow dr in MergeTable.Rows)
                {
                    if (dr.RowState == DataRowState.Unchanged)
                    {
                        dr.SetAdded();
                    }
                    //Entfernen von doppelten Zeilen zur Änderung einzelner values
                    DataRow doubleRow = UpdateTable.Rows.Find(dr[0].ToString());
                    if (doubleRow != null)
                    {
                        doubleRow.Delete();
                    }
                }
                UpdateTable.Merge(MergeTable);
                MessageBox.Show("Merge abgeschlossen.");
            }

            try
            {
                da.Update(UpdateTable);
                success = true;
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error has occured!" + ex.Message);
                success = false;
            }
        }
        return success;
    }

Basically I just delete all duplicate rows before i merge and update, works fine for me but probably not the ideal solution.

How to override values in merging DataTables using .Merge() method?

1 Answers1