How to make the current status as 'open' for executereader

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1.00/5 (1 vote)

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Hi,

I got the below error

"ExecuteReader requires an open and available Connection. The connection's current state is closed"

I'm trying to do the coding for the auto-increment serial numbers. Please help me to clear this error.

What I have tried:

class Generator
    {
        public static void autoincrement(string sqlquery, Control textbox)
        {
            SqlConnection con = Connection.GetConnection();
            con.Open();
            SqlCommand cmd = new SqlCommand(sqlquery, Connection.GetConnection());
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                string value = dr[0].ToString();
                if (value == "")
                {
                    textbox.Text = "111";
                }
                else
                {
                    textbox.Text = dr[0].ToString();
                }
            }
            
            con.Close();

        }
    }

Posted 6-Dec-20 21:37pm

ishuishika

Updated 6-Dec-20 21:49pm

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OriginalGriff · Accepted Answer · 2020-12-06T21:49:00

Look at your code: You create a connection:

C#

SqlConnection con = Connection.GetConnection();

You open it:

C#

con.Open();

And you then ignore it and create another:

C#

SqlCommand cmd = new SqlCommand(sqlquery, Connection.GetConnection());

Use the one you just opened, and it'll work:

C#

SqlCommand cmd = new SqlCommand(sqlquery, con);

I'd strongly suggest that you look at using blocks though - they ensure teh connection is correctly closed and disposed when you are finished with it:

C#

using (SqlConnection con = Connection.GetConnection())
   {
   con.Open();
   using (SqlCommand cmd = new SqlCommand(sqlquery, con))
      {
      using (SqlDataReader dr = cmd.ExecuteReader())
         {
         if (dr.Read())
            {
            string value = dr[0].ToString();
            if (string.IsNullOrWhitespace(value))
               {
               textbox.Text = "111";
               }
            else
               {
               textbox.Text = value;
               }
            }
        }
    }