Connection was not closed.the connection's current state is open

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my code is below there is a error while running(i.e) connection was not closed,the connection's current state is open.

What I have tried:

C#

private void button2_Click(object sender, EventArgs e)
        {
            con.Open();
            
            OleDbCommand delcmd = new OleDbCommand();
            //if (dataGridView1.Rows.Count > 1 && dataGridView1.SelectedRows[0].Index != dataGridView1.Rows.Count-1)
            if(dataGridView1.SelectedRows.Count > 0 && dataGridView1.SelectedRows[0].Index!=dataGridView1.Rows.Count-1)
            
            {
                delcmd.CommandText = "delete from table123 where Idno=" + dataGridView1.SelectedRows[0].Cells[0].Value.ToString() + "";
               
                delcmd.Connection = con;
                delcmd.ExecuteNonQuery();
                con.close();
                dataGridView1.Rows.RemoveAt(dataGridView1.SelectedRows[0].Index);
                MessageBox.Show("Row Deleted");
                bind();
                clear();
            }
}

Posted 22-Feb-17 20:10pm

Member 13006682

Updated 22-Feb-17 20:31pm

Graeme_Grant

v2

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Comments

Richard Deeming 23-Feb-17 15:36pm

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

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Michael_Davies · Answer 1 · 2017-02-22T20:31:00

The close for the connection is embedded within an if condition, move it outside of the if as it will only close if the condition is true and you should close the connection regardless of the condition.

C#

private void button2_Click(object sender, EventArgs e)
        {
            //if (dataGridView1.Rows.Count > 1 && dataGridView1.SelectedRows[0].Index != dataGridView1.Rows.Count-1)
            if(dataGridView1.SelectedRows.Count > 0 && dataGridView1.SelectedRows[0].Index!=dataGridView1.Rows.Count-1)
            
            {
                using (OleDbCommand delcmd = new OleDbCommand())
                {
                   delcmd.CommandText = "delete from table123 where Idno=@ID";
               
                   delcmd.Connection = con;
                   delcmd.Parameters.Add("@ID", dataGridView1.SelectedRows[0].Cells[0]);

                   con.Open();
                   delcmd.ExecuteNonQuery();
                   con.close();
                }
                dataGridView1.Rows.RemoveAt(dataGridView1.SelectedRows[0].Index);
                MessageBox.Show("Row Deleted");
                bind();
                clear();
            }

}

Improved answer, no need to open connection if nothing to do, added proper parameterised string.