The connection was not closed. The connection's current state is open.

Question

1.00/5 (1 vote)

See more:

Hi,
Please help me with this, I have already closed the connection but still, I get the same error.

What I have tried:

if (Validation())
            {
                
                // Insert Logic
                con.Open();

                
                if (ifComponentsExist(con, textBox1.Text))
                {
                    sqlquery = @"UPDATE [Components]SET [APartNo] = '" + textBox8.Text + "',[Availability] = '" + textBox3.Text + "',[Quantity] = '" + textBox4.Text + "',[Date] ='" + dateTimePicker1.Value.ToString() + "',[Amount] = '" + textBox7.Text + "',[CompDiscription] = '" + textBox2.Text + "',[CompanyName] = '" + textBox5.Text + "',[Stored On] = '" + comboBox1.Text + "',[Stored No] = '" + textBox9.Text + "' WHERE [CompPartNo] = '" + textBox1.Text + "'";
                }
                else
                {
                    sqlquery = @"INSERT INTO [IMS].[dbo].[Components]([APartNo],[CompPartNo],[CompDiscription],[Availability],[Quantity],[CompanyName],[Amount],[Date],[Stored On])
                    VALUES
                          ('" + textBox8.Text + "','" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "','" + textBox4.Text + "','" + textBox5.Text + "','" + textBox7.Text + "','" + dateTimePicker1.Value.ToString() + "','" + comboBox1.Text + "','" + textBox9.Text + "')";
                }

                SqlCommand cmd2 = new SqlCommand(sqlquery, con);
                cmd2.ExecuteNonQuery();

                con.Close();

Posted 11-Nov-20 18:38pm

ishuishika

Updated 11-Nov-20 19:53pm

Add a Solution

2 solutions

Solution 1

There might be some error. Debugging should tell the flow of execution.

To be on safer side, follow the best practice by:
Option 1: Put the ado.net code in a try-finally[^]

Quote:
By using a finally block, you can clean up any resources that are allocated in a try block, and you can run code even if an exception occurs in the try block.

C#

try
{
  //
}
finally
{
   con.close();
}

Option 2: Use using statement[^]

Quote:
Provides a convenient syntax that ensures the correct use of IDisposable objects

C#

using(var con = new SqlConnection(connectionString))
{
  // code
}

Posted 11-Nov-20 18:58pm

Sandeep Mewara

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2020-11-11T19:53:00

Don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

BTW: Do yourself a favour, and stop using Visual Studio default names for everything - you may remember that "TextBox8" is the mobile number today, but when you have to modify it in three weeks time, will you then? Use descriptive names - "tbMobileNo" for example - and your code becomes easier to read, more self documenting, easier to maintain - and surprisingly quicker to code because Intellisense can get to to "tbMobile" in three keystrokes, where "TextBox8" takes thinking about and 8 keystrokes...

[edit]
And another thing: it's a bad practice to "recycle" a single global Connection object - it leads to some really nasty problems later if you aren't very careful.
Create your SqlConnection object inside a using block when you need it, Open it, use it, and let the block Dispose it when you are finished:

C#

using (SqlConnection con = new SqlConnection(strConnect))
    {
    con.Open();
    using (SqlCommand cmd = new SqlCommand("INSERT INTO myTable (myColumn1, myColumn2) VALUES (@C1, @C2)", con))
        {
        cmd.Parameters.AddWithValue("@C1", myValueForColumn1);
        cmd.Parameters.AddWithValue("@C2", myValueForColumn2);
        cmd.ExecuteNonQuery();
        }
    }

[/edit]