我正在寫一個C#窗體窗體應用程序,我來到上面提到的錯誤。我認爲這是因爲我在我的主窗體加載對象中打開一個sql連接和閱讀器對象,然後在另一個單擊事件處理程序中再次做同樣的事情。我不確定我需要做什麼來改變我的代碼/阻止這種情況的發生(或者甚至是這個問題)。我試圖在我的連接字符串中打開MARS,但這並沒有解決問題。以下是我的代碼。無法重用打開DataReader
namespace Excel_Importer
{
public partial class Export : Form
{
public Export()
{
InitializeComponent();
}
private void cmbItemLookup_SelectedIndexChanged(object sender, EventArgs e)
{
}
private void Export_Load(object sender, EventArgs e)
{
string connectionString = ConfigurationManager.ConnectionStrings ["dbconnection"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connectionString))
{
conn.Open();
SqlCommand cmd = new SqlCommand("Select * From ExportItem", conn);
SqlDataReader rdr;
rdr = cmd.ExecuteReader();
System.Data.DataTable dt = new System.Data.DataTable();
dt.Columns.Add("ExportItemName", typeof(string));
dt.Load(rdr);
cmbItemLookup.DisplayMember = "ExportItemName";
cmbItemLookup.DataSource = dt;
conn.Close();
}
}
private void btnLoad_Click(object sender, EventArgs e)
{
string connectionString = ConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString;
SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
SqlCommand cmd2 = new SqlCommand("Select * from " + cmbItemLookup.Text, conn);
SqlDataReader rdr2;
rdr2 = cmd2.ExecuteReader();
try
{
SqlDataAdapter ada = new SqlDataAdapter();
ada.SelectCommand = cmd2;
DataTable dt = new DataTable();
ada.Fill(dt);
BindingSource bs = new BindingSource();
bs.DataSource = dt;
dgvExport.DataSource = bs;
ada.Update(dt);
conn.Close();
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message);
}
}
}
}