选择组合框时如何获取数据 windows Form c#

Question

private void namecombo_SelectedIndexChanged(object sender, EventArgs e)
        {
            using (SqlConnection sqlconn = new SqlConnection(@"Data Source=DESKTOP-IIBSL6N;Initial Catalog=sales_management;Integrated Security=True"))
            {
                sqlconn.Open();
                SqlCommand sqlcmd = new SqlCommand("SELECT * FROM Customer WHERE Name = '" + this.namecombo.SelectedItem.ToString() + "' ", sqlconn);
                sqlcmd.ExecuteNonQuery();
                DataTable dtbl = new DataTable();
                SqlDataAdapter adapter = new SqlDataAdapter(sqlcmd);
                adapter.Fill(dtbl);
                foreach(DataRow dr in dtbl.Rows)
                {
                    accountnumtxtbox.Text = dr["acount_name"].ToString();
                    phonetxtbox.Text = dr["phone_number"].ToString();
                    officenumtxtbox.Text = dr["office_number"].ToString();
                    addresstxtbox.Text = dr["Address"].ToString();
                }
                sqlconn.Close();
            }
        }

this doesn't work at all whats the problem?

Answer 1

using (SqlConnection sqlconn = new SqlConnection(@"Data Source=DESKTOP-IIBSL6N;Initial Catalog=sales_management;Integrated Security=True"))   
{  
    sqlconn.Open();  
    SqlCommand sqlcmd = new SqlCommand("SELECT * FROM Customer WHERE Name = N'" + this.customergrid.SelectedRows + "' ", sqlconn);  
    sqlcmd.ExecuteNonQuery();  
    DataTable dtbl = new DataTable();  
    SqlDataAdapter adapter = new SqlDataAdapter(sqlcmd);  
    adapter.Fill(dtbl);  
    foreach (DataRow dr in dtbl.Rows)  
    {  
        accountnumtxtbox.Text = dr["acount_name"].ToString();  
        phonetxtbox.Text = dr["phone_number"].ToString();  
        officenumtxtbox.Text = dr["office_number"].ToString();  
        addresstxtbox.Text = dr["Address"].ToString();  
    }  
    sqlconn.Close();  
}  

Answer 2

You try to do it this way, just adapt it to your needs.

string sql = "SELECT * FROM Customers WHERE LastName = @lastName AND FirstName = @firstName";
        UserAccount account = UserAccount.Empty;

        using (SqlCommand cmd = new SqlCommand(sql, sqlConnection))
        {
            SqlParameter _firstName = new SqlParameter("@firstName", SqlDbType.NVarChar);
            SqlParameter _lastName = new SqlParameter("@lastName", SqlDbType.NVarChar);

            _firstName.Value = account.FirstName;
            _lastName.Value = account.LastName;

            cmd.Parameters.Add(_firstName);
            cmd.Parameters.Add(_lastName);

            DataSet dataSet = new DataSet();

            SqlDataAdapter adapter = new SqlDataAdapter(cmd);

            adapter.Fill(dataSet);

            if (dataSet.Tables.Count > 0)
            {
                if (dataSet.Tables[0].Rows.Count > 0)
                {
                    DataRow row = dataSet.Tables[0].Rows[0];

                    //fill your properties with the results
                }
            }

            adapter.Dispose();
            dataSet.Dispose();
        }