c# db access save,hapus,cari

namespace nilaiPrj

{

    public partial class Form1 : Form

    {

        OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\syamsul\akhir.accdb");

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            con.Open();

            string sql = "SELECT * FROM nilai";

            OleDbDataAdapter da = new OleDbDataAdapter(sql, con);

            DataSet ds = new DataSet();

            da.Fill(ds,"nilai");

            grid1.DataSource = ds.Tables["nilai"].DefaultView;

        }

        private void bsimpan_Click(object sender, EventArgs e)

        {

string sql = string.Format("insert into nilai values('{0}','{1}','{2}')", textBox1.Text, textBox2.Text, textBox3.Text);

            OleDbCommand cmd = new OleDbCommand(sql, con);

            cmd.ExecuteNonQuery();

            MessageBox.Show("Data berhasil disimpan");

            cmd.Dispose();

           
        string tampil = "SELECT * FROM nilai";
            OleDbDataAdapter da = new OleDbDataAdapter(tampil, con);
            DataSet ds = new DataSet();
            da.Fill(ds, "nilai");
            grid1.DataSource = ds.Tables["nilai"].DefaultView;
            grid1.Refresh();

        }

        private void bcari_Click(object sender, EventArgs e)

        {

            OleDbDataReader dt = null;

            string sql = string.Format("select * from nilai where nim = '{0}'", textBox1.Text);

            OleDbCommand cmd = new OleDbCommand(sql, con);

            dt = cmd.ExecuteReader();

            if (dt.Read())

            {

                textBox2.Text = Convert.ToString(dt["nilaiuts"]);

                textBox3.Text = Convert.ToString(dt["nilaiuas"]);

            }

            else

            { MessageBox.Show("dt td ada"); }

        }

        private void bhapus_Click(object sender, EventArgs e)

        {

            string sql = string.Format("delete * from nilai where nim='" + textBox1.Text + "'");

            OleDbCommand cmd = new OleDbCommand(sql, con);

            cmd.ExecuteNonQuery();

            con.Close();

            MessageBox.Show("Data Telah Dihapus");

        }

        private void bupdate_Click(object sender, EventArgs e)

        {

            string sql = string.Format("update nilai set nama=@name where nim=@nim",con);

            //con.Open();

           

            OleDbCommand cmd = new OleDbCommand(sql, con);

            cmd.Parameters.AddWithValue("@name", textBox2.Text);

            cmd.ExecuteNonQuery();

            MessageBox.Show("Data berhasil diupdate");

            cmd.Dispose();

          

        }

    }

}