Editing data tables

Many possibilities are available to edit table data. This sample demostrates to edit data (insert and update records) via a datagridview (cell value event) events.

Postgres and C#

Insert new records to a certain table

  void insertNewMap(string fileName) // 
        {
            using (NpgsqlConnection cnn = new NpgsqlConnection(cnsb.ConnectionString))
            {
                cnn.Open();
                using (NpgsqlCommand cmd = new NpgsqlCommand())
                {
                    string seq_mapid;
                    string gr_id = cmbGroups.SelectedValue.ToString();
                    string grformat = System.IO.Path.GetExtension(fileName).Replace(".","");
                    NpgsqlDataAdapter da = new NpgsqlDataAdapter("select nextval('seq_mapid')", cnn);       // select nextval('seq_mapid') command generates the next PK value
                    DataTable dt = new DataTable();
                    da.Fill(dt);
                    seq_mapid = dt.Rows[0][0].ToString();
                    cmd.Connection = cnn;
                    string sqlCommand = "INSERT INTO " + tableName + " (title, map_id, group_id, grformat) VALUES ('" + System.IO.Path.GetFileName(fileName) + "'," + seq_mapid.ToString() + ",'" + gr_id + "','" + grformat + "')";
                    cmd.CommandText = sqlCommand;
                    try
                    {
                        cmd.ExecuteNonQuery();
                    }
                    catch (Exception error)
                    {                        
                        MessageBox.Show("Error in INSERT command: " + error.Message,"Error in INSERT",MessageBoxButtons.OK,MessageBoxIcon.Error);
                    }
                    System.IO.File.Copy(fileName, mapPath + seq_mapid + System.IO.Path.GetExtension(fileName));
                }
            }
        }

Update a field of a certain record and table

        private void dgv_CellValueChanged(object sender, DataGridViewCellEventArgs e)       //if a cell value of datagrid has changed, this event occurs
        {
            using (NpgsqlConnection cnn = new NpgsqlConnection(cnsb.ConnectionString))
            {
                cnn.Open();
                using (NpgsqlCommand cmd = new NpgsqlCommand())
                {
                    cmd.Connection = cnn;
                    string updateColumnName = dgv.Columns[e.ColumnIndex].Name;
                    string updateColumnValue = dgv.Rows[e.RowIndex].Cells[e.ColumnIndex].Value.ToString();

                    string updateCommand="";
                    updateCommand = "UPDATE " + tableName + " SET " + updateColumnName + "='" + updateColumnValue + "' WHERE map_id=" + dgv.Rows[selectedMapID].Cells["map_id"].Value; //mapId is the PK
                    cmd.CommandText = updateCommand;
                    cmd.ExecuteNonQuery();
                }
            }
        }