ExecuteReader: Connection property has not been initialized.

Question

0.00/5 (No votes)

See more:

C#

string s = "select * from "+U_name.Text+" where Physics_Topic='"+grdTopicname.Text+"'";
        SqlCommand cmd = new SqlCommand(s, con);
        cmd.Connection = con;
        SqlDataReader dr = cmd.ExecuteReader();
        dr.Read();
        if (dr.HasRows)
        {
            dr.Read();
            string s1 = "update " + U_name.Text + " set TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='"+Result.Text+"'";
            con.Open();
            cmd.ExecuteNonQuery();
            
        }
        else
        {
            string s2 = "insert into" + U_name.Text + "where TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
            con.Open();
            cmd.ExecuteNonQuery();

plz help me sir

Posted 17-Dec-14 17:14pm

iamvinod34

Updated 17-Dec-14 17:17pm

Garth J Lancaster

v2

Add a Solution

2 solutions

Solution 1

well, for a start, you

a) don't tell us where you get that error - for example, at the dr.read() on line 5?
b) use 'con' on lines 2,3 but don't issue an open until line 11,17
c) you havnt shown us where & how you initialise 'con'

so it might be a bit hard for us to see whats going on

Posted 17-Dec-14 17:22pm

Garth J Lancaster

Comments

iamvinod34 17-Dec-14 23:32pm

SqlDataReader dr = cmd.ExecuteReader(); get eror

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)

George Jonsson · Accepted Answer · 2014-12-17T17:35:00

Solution 2

It looks like you try to use the reader before you open the connection.

C#

string s = "select * from "+U_name.Text+" where Physics_Topic='"+grdTopicname.Text+"'";
con.Open();   // Moved this statement here.
SqlCommand cmd = new SqlCommand(s, con);
cmd.Connection = con;
SqlDataReader dr = cmd.ExecuteReader();
dr.Read();
if (dr.HasRows)
{
    dr.Read();
    string s1 = "update " + U_name.Text + " set TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='"+Result.Text+"'";
    cmd.ExecuteNonQuery();
}
else
{
    string s2 = "insert into" + U_name.Text + "where TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
    cmd.ExecuteNonQuery();
    con.Close();   // Also close the connection

That said, there are a few things you should correct in your code.

1. Use using statements for connections. It will automatically close your connection.

C#

using (SqlConnection con = new SqlConnection(connectionString))
{
    // Put the rest of your code here
}

2. Also use using for readers for the same reason

C#

using (SqlDataReader dr = cmd.ExecuteReader())
{
    // Reading code here
}

3. Use paramterized SQL commands
This makes your life easier when it comes to change the SQL commands and it prevents from injection of malicious code.
SqlCommand.Parameters[^]

Posted 17-Dec-14 17:35pm

George Jonsson

Comments

iamvinod34 17-Dec-14 23:41pm

The ConnectionString property has not been initialized.
con.open();

George Jonsson 17-Dec-14 23:52pm

What do you mean?
Haven't you initialized with a connection string?

iamvinod34 17-Dec-14 23:57pm

yes sir
my code :
{

string s = "select * from " + U_name.Text + " where Physics_Topic='" + grdTopicname.Text + "'";
con.Open();
SqlCommand cmd = new SqlCommand(s, con);
cmd.Connection = con;

using (SqlDataReader dr = cmd.ExecuteReader())
{
dr.Read();
if (dr.HasRows)
{
dr.Read();
string s1 = "update " + U_name.Text + " set TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
cmd.ExecuteNonQuery();

}
else
{
string s2 = "insert into" + U_name.Text + "where TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
cmd.ExecuteNonQuery();
con.Close();
}
}

}

George Jonsson 18-Dec-14 0:01am

So where does it fail?
You understand I cannot execute your code, right?

iamvinod34 18-Dec-14 0:08am

no sir
using (SqlConnection con = new SqlConnection(connectionString))
{
con.Open();
string s = "select * from " + U_name.Text + " where Physics_Topic='" + grdTopicname.Text + "'";

SqlCommand cmd = new SqlCommand(s, con);
cmd.Connection = con;

using (SqlDataReader dr = cmd.ExecuteReader())
{
dr.Read();
if (dr.HasRows)
{
dr.Read();
string s1 = "update " + U_name.Text + " set TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
cmd.ExecuteNonQuery();

}
else
{
string s2 = "insert into" + U_name.Text + "where TopicID='" + grdID.Text + "',Physics_Topic='" + grdTopicname.Text + "',Physics_score='" + Result.Text + "'";
cmd.ExecuteNonQuery();
con.Close();
}
}

}
The ConnectionString property has not been initialized.
Line 266: using (SqlConnection con = new SqlConnection(connectionString))
Line 267: {
Line 268: con.Open();
Line 269: string s = "select * from " + U_name.Text + " where Physics_Topic='" + grdTopicname.Text + "'";
Line 270:

George Jonsson 18-Dec-14 0:10am

Please stop posting the same code over and over in the comments!!

what is the contents of the variable connectionString ?