private void comboBox1_DropDown(object sender, EventArgs e)
{
SqlConnection sqlcon = new SqlConnection(@"data source=SERGM\SQLEXPRESS;initial catalog=informatica;" +
"integrated security=sspi");
try
{
sqlcon.Open();
if (sqlcon.State == ConnectionState.Open)
{
int i;
comboBox1.Items.Clear();
SqlCommand sqlcom = new SqlCommand("sSemestr", sqlcon);
sqlcom.ExecuteNonQuery();
sqlcom.CommandType = CommandType.StoredProcedure;
DataSet ds = new DataSet();
SqlDataAdapter da = new SqlDataAdapter("sSemestr", sqlcon);
da.Fill(ds, "sSemestr");
DataTable dt = ds.Tables[ 0 ];
for (i =  0 ; i < ds.Tables[ 0 ].Rows.Count; i++)
{
DataRow dr = dt.Rows[i];
comboBox1.Items.Add(dr[ 0 ]);
}
}
}
catch (Exception)
{
if (sqlcon.State != ConnectionState.Open)
{
MessageBox.Show("подключения не существует");
}
}
finally
{
if (sqlcon.State == ConnectionState.Open)
{
sqlcon.Close();
}
}
}

 
DataSet ds = new DataSet();

private void button1_Click(object sender, EventArgs e)
{
string str = comboBox1.Text;
SqlConnection sqlcon = new SqlConnection(@"data source=SERGM\SQLEXPRESS;initial catalog=informatica;" +
"integrated security=sspi");
//comboBox3.Items.Clear();
SqlCommand sqlcom = new SqlCommand("sNedelya", sqlcon);
ds.Clear();
SqlDataAdapter da = new SqlDataAdapter("sNedelya", sqlcon);

//sqlcom.UpdatedRowSource = UpdateRowSource.Both ;

sqlcon.Open();
try
{

if (sqlcon.State == ConnectionState.Open)
{
dataGridView1.DataSource = null;

// MessageBox.Show(comboBox3.Text);
sqlcom.CommandType = CommandType.StoredProcedure;
sqlcom.Parameters.AddWithValue("@semestr",comboBox1.SelectedText);
sqlcom.ExecuteNonQuery();
da.Fill(ds, "sNedelya");

//DataTable dt = ds.Tables[ 0 ];

dataGridView1.DataSource = ds;
dataGridView1.DataMember = "sNedelya";

//comboBox1.Text = dataGridView1.CurrentRow.Cells[ 0 ].Value.ToString();
//dateTimePicker1.Text = dataGridView1.CurrentRow.Cells[ 1 ].Value.ToString();
//dateTimePicker2.Text = dataGridView1.CurrentRow.Cells[ 2 ].Value.ToString();
}
}
catch (Exception)
{
if (sqlcon.State != ConnectionState.Open)
{
MessageBox.Show("подключения не существует");
}
}
finally
{
sqlcon.Close();
}

}