C#代码错误-未关闭连接. [英] Error in C# code - The connection was not closed.

问题描述

当我运行此代码时，它将引发错误消息连接未关闭.连接的当前状态为打开".在尝试打开连接的尝试块之后.
有人可以帮我解决这个问题吗?

When I run this code it throws an error sayng "The connection was not closed. The connection''s current state is open." exactly after try block where I open the connection.
Can anybody help me to solve this please??

private void btnAdd_Click(object sender, EventArgs e)
{
    try
    {
        // Connection Open

        newConnection.conn.Open();


        string updSql = "Insert Into tblCustomer values (@CustomerID, @FirstName, @LastName, @Age, @DOB, @Address, @NID, @Registered_Date, @Registration_Fee, @Fine, @No_Of_Books, @Borrow_Date, @Date_should_Return, @Return_Date, @Over_Due, @Fine_per_Day)";

        SqlCommand cmdupd = new SqlCommand(updSql, newConnection.conn);


        cmdupd.Parameters.Add(new SqlParameter("@CustomerID", SqlDbType.NChar));
        cmdupd.Parameters["@CustomerID"].Value = txtCustomerID1.Text;

        cmdupd.Parameters.Add(new SqlParameter("@FirstName", SqlDbType.VarChar,100));
        cmdupd.Parameters["@FirstName"].Value = txtFirstName.Text;

        cmdupd.Parameters.Add(new SqlParameter("@LastName", SqlDbType.VarChar, 100));
        cmdupd.Parameters["@LastName"].Value = txtLastName.Text;

        cmdupd.Parameters.Add(new SqlParameter("@Address", SqlDbType.VarChar, 250));
        cmdupd.Parameters["@Address"].Value = txtAddress.Text;

        cmdupd.Parameters.Add(new SqlParameter("@DOB", SqlDbType.DateTime));
        cmdupd.Parameters["@DOB"].Value = DateTime.Today;

        cmdupd.Parameters.Add(new SqlParameter("@Age", SqlDbType.Decimal));
        cmdupd.Parameters["@Age"].Value = Convert.ToDecimal(txtAge.Text);

        cmdupd.Parameters.Add(new SqlParameter("@NID", SqlDbType.NChar));
        cmdupd.Parameters["@NID"].Value = txtNID.Text;

        cmdupd.Parameters.Add(new SqlParameter("@Registered_Date", SqlDbType.DateTime));
        cmdupd.Parameters["@Registered_Date"].Value = DateTime.Today;

        cmdupd.Parameters.Add(new SqlParameter("@Registration_Fee", SqlDbType.Decimal));
        cmdupd.Parameters["@Registration_Fee"].Value = Convert.ToDecimal(txtRegistFee.Text);

        cmdupd.Parameters.Add(new SqlParameter("@Fine", SqlDbType.Decimal));
        cmdupd.Parameters["@Fine"].Value = 0;

        cmdupd.Parameters.Add(new SqlParameter("@No_Of_Books", SqlDbType.Decimal));
        cmdupd.Parameters["@No_Of_Books"].Value = 0;

        cmdupd.Parameters.Add(new SqlParameter("@Borrow_Date", SqlDbType.DateTime));
        cmdupd.Parameters["@Borrow_Date"].Value = DateTime.Today;

        cmdupd.Parameters.Add(new SqlParameter("@Date_should_Return", SqlDbType.DateTime));
        cmdupd.Parameters["@Date_should_Return"].Value = DateTime.Today;

        cmdupd.Parameters.Add(new SqlParameter("@Return_Date", SqlDbType.DateTime));
        cmdupd.Parameters["@Return_Date"].Value = DateTime.Today;

        cmdupd.Parameters.Add(new SqlParameter("@Over_Due", SqlDbType.Decimal));
        cmdupd.Parameters["@Over_Due"].Value = 0;

        cmdupd.Parameters.Add(new SqlParameter("@Fine_per_Day", SqlDbType.Decimal));
        cmdupd.Parameters["@Fine_per_Day"].Value = 0;


        cmdupd.ExecuteNonQuery();
        newConnection.conn.Close();
        MessageBox.Show("New Customer Detail Updated.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);

    }
    catch (SqlException e1)
    {
        Console.WriteLine(e1.ErrorCode);
        Console.WriteLine(e1.Message);
        if (e1.Number == 2627)
        {
            MessageBox.Show("Duplicate Customer ID.", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Error);
            newConnection.conn.Close();
            this.txtCustomerID1.Focus();
        }

    }

}

推荐答案

好吧，看看它是否类似于此处 [

Well, just see if it is something like this issue[^].

Surely, you have already opened up the connection and trying to re-open. Use DEBUGGER and see what''s the case.
Just in case, if needed, have a look at various experiences and reason of this error here[^]. Using try-catch-finally and ''using'' blocks are few of the best practices related to Connections.

请使用finally块关闭连接.
也许代码中的某些地方引发了异常，因此无法关闭连接.为确保连接状态，请使用

Please use finally block to Close the connection.
Maybe there are some places in your code raised an exception, so that the connection cannot be Closed. To ensure the state of the Connection, please use

if (conn.State == ConnectionState.Closed)
        {
            conn.Open()
        }

问候，
安迪

Regards,
Andy

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