static string exePath = System.Environment.CurrentDirectory;//本程序所在路徑

//創建連接對象
OleDbConnection conn = new OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;data source=" + exePath + @"/文件名.mdb");

private void 獲取數據表/查詢()
{
    conn.Open();

    //獲取數據表
    //string sql = "select * from 表名 order by 字段1";
    //查詢
    string sql = "select * from 表名 where 字段2="...;

    OleDbDataAdapter da = new OleDbDataAdapter(sql, conn); //創建適配對象
    DataTable dt = new DataTable(); //新建表對象
    da.Fill(dt); //用適配對象填充表對象
    dataGridView1.DataSource = dt; //將表對象作為DataGridView的數據源

    conn.Close();
}

private void 增/刪/改()
{
     conn.Open();

     //增
     string sql = "insert into 表名(字段1,字段2,字段3,字段4)values(...)";
     //刪
     //string sql = "delete from 表名 where 字段1="...;
     //改
     //string sql = "update student set 學號=" ...;

     OleDbCommand comm = new OleDbCommand(sql, conn);

     comm.ExecuteNonQuery();

     conn.Close();
}

int i = comm.ExecuteNonQuery();
if (i > 0)
{
      MessageBox.Show("添加數據成功!", "操作提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
{
      MessageBox.Show("添加失敗!", "操作提示", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

private void saveData2()
{
     dataGridView1.EndEdit();

     string sql = "select * from 表名";

     OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);

     OleDbCommandBuilder bld = new OleDbCommandBuilder(da);
     da.UpdateCommand = bld.GetUpdateCommand();

        //把DataGridView賦值給dataTbale。(DataTable)的意思是類型轉換，前提是后面緊跟著的東西要能轉換成dataTable類型
     DataTable dt = (DataTable)dataGridView1.DataSource;

     da.Update(dt);
     dt.AcceptChanges();

     conn.Close();
}