many statements

I need to add datagridview data to ms access table, at the same time add a column into that table and update the column as well. please help me, I keep getting an error that says.. Syntax error in field definition and then says No value given for one or more required parameters.Your help will be appreciated.Check my code and correct me.Thank You.

private void button1_Click(object sender, EventArgs e)
        {
            string myConnectionString = " ";

            myConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:/Users/game/Desktop/3rd year/2nd Semester/INYM 328/EmployeeAttendanceRegister/EmployeeAttendanceRegister/EmployeeAttendanceRegister.accdb";
            OleDbConnection myConnection = new OleDbConnection(myConnectionString);

            string col1 = dataGridView1[0, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col2 = dataGridView1[1, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col3 = dataGridView1[2, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col4 = dataGridView1[3, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col5 = dataGridView1[4, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col6 = dataGridView1[5, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string col7 = dataGridView1[6, dataGridView1.CurrentCell.RowIndex].Value.ToString();
            string myInsertQuery = "INSERT INTO Attendance VALUES('" + col1 + "','" + col2 + "','" + col3 + "','" + col4 + "','" + col5 +"','" + col6 + "','" + col7 + "')";

            OleDbCommand myCommand = new OleDbCommand(myInsertQuery);
            myCommand.Connection = myConnection;

            myConnection.Open();
            try
            {
                myCommand.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString());
            }
            myConnection.Close();
            {
                string myConn = " ";

                myConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:/Users/game/Desktop/3rd year/2nd Semester/INYM 328/EmployeeAttendanceRegister/EmployeeAttendanceRegister/EmployeeAttendanceRegister.accdb";
                OleDbConnection myCon = new OleDbConnection(myConn);

                string myInsert = "ALTER TABLE Attendance ADD COLUMN SignIn";
                OleDbCommand myCom = new OleDbCommand(myInsert);
                myCom.Connection = myCon;

                myCon.Open();
                try
                {
                    myCom.ExecuteNonQuery();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message.ToString());
                }
                myCon.Close();
            }
            {
                string myString = " ";

                myString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:/Users/game/Desktop/3rd year/2nd Semester/INYM 328/EmployeeAttendanceRegister/EmployeeAttendanceRegister/EmployeeAttendanceRegister.accdb";
                OleDbConnection myConnect = new OleDbConnection(myString);
                string Insert = "UPDATE Attendance SET SignIn = '" + dateTimePicker1.Value + "'";

                OleDbCommand myComm = new OleDbCommand(Insert);
                myComm.Connection = myConnect;

                myConnect.Open();
                try
                {
                    myComm.ExecuteNonQuery();

                    MessageBox.Show("Successfully Signed IN");
                    frmhomepage previousForm = new frmhomepage();
                    previousForm.Show();
                    this.Hide();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message.ToString());
                }

                myConnect.Close();
            }
        }

---

kbundas