[英]C# Execute sql query in backgroundworker
我有一個 winforms 應用程序,它通過在登錄前檢查用戶權限、用戶名和密碼是否匹配來登錄用戶。數據庫目前只有三個用戶用於測試目的。
我面臨的問題是,每當我嘗試登錄時,程序都會在登錄前凍結至少 30 秒。我到處搜索以找到解決方案。 我試過一個后台工作人員,但是,這對我也不起作用; 也許我用錯了。
這是用於登錄的代碼
登錄名.cs
private void btnLogin_Click(object sender, EventArgs ev)
{
try
{
SqlDataAdapter sda = new SqlDataAdapter("Select count(*) from Logins where Username='" + txtUserName.Text + "' and Password='" + txtPassword.Text + "' and Type='" + cbType.Text + "'", scon);
DataTable dt = new DataTable();
sda.Fill(dt);
if (dt.Rows[0][0].ToString() == "1")
{
sda1 = new SqlDataAdapter("Select Type from Logins where Username='" + txtUserName.Text + "' and Password='" + txtPassword.Text + "'", scon);
dt1 = new DataTable();
sda1.Fill(dt1);
//Check if user matches with admin then log them in
if (dt1.Rows[0][0].ToString() == "Admin")
{
lblMessage.Text = "Logging Successful!";
SnackBarTimer();
Hide();
AdminForm admin = new AdminForm();
admin.Show();
}
//Check if user matches with secretary then log them in
if (dt1.Rows[0][0].ToString() == "Secretary")
{
lblMessage.Text = "Logging Successful!";
SnackBarTimer();
Hide();
frmMain main = new frmMain();
main.Show();
}
//Check if user matches with employee then log them in
if (dt1.Rows[0][0].ToString() == "Employee")
{
}
lblMessage.Text = "Logging In...";
SnackBarTimer();
}
}
catch (Exception ex)
{
lblMessage.Text = ex.Message;
SnackBarTimer();
}
finally
{
scon.Close();
}
}
我無法消除延遲,但是我想出了如何正確實施后台工作人員,因此現在表單不再凍結。 我還添加了一個進度條來顯示某種形式的進度。
登錄按鈕點擊事件:
private void btnLogin_Click(object sender, EventArgs ev)
{
//
//If background worker busy, show snackbar and login after
//
if (!bgw.IsBusy)
{
pnlSnackBar.Visible = true;
lblMessage.Text = "Logging In...Please wait";
SnackBarTimer();
bgw.RunWorkerAsync();
}
}
后台工作者:
private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
try
{
cmd = new SqlCommand("Select Type from Logins where Username='@user' and Password='@pass'", scon);
cmd.Parameters.AddWithValue("@user", txtUserName.Text);
cmd.Parameters.AddWithValue("@pass", txtPassword.Text);
sda1 = new SqlDataAdapter(cmd);
dt1 = new DataTable();
sda1.Fill(dt1);
}
catch (Exception ex)
{
//pnlSnackBar.Visible = true;
lblMessage.Text = ex.Message;
SnackBarTimer();
}
}
后台工作完成:
private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
try
{
if (dt1.Rows.Count == 1)
{
if (dt1.Rows[0][0].ToString() == "Admin")
{
LoginInfo.UserID = txtUserName.Text;
Hide();
AdminForm admin = new AdminForm();
admin.Show();
}
if (dt1.Rows[0][0].ToString() == "Secretary")
{
LoginInfo.UserID = txtUserName.Text;
Hide();
frmMain main = new frmMain();
main.Show();
}
if (dt1.Rows[0][0].ToString() == "Employee")
{
LoginInfo.UserID = txtUserName.Text;
Hide();
EmployeeForm employee = new EmployeeForm();
employee.Show();
}
}
}
catch (Exception ex)
{
pnlSnackBar.Visible = true;
lblMessage.Text = ex.Message;
SnackBarTimer();
}
}
進度改變:
private void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
metroProgressSpinner.Value = e.ProgressPercentage;
}
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