I got this Error in program

Question

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C#

protected void txtLogin_Click(object sender, EventArgs e) {
        string ConnectionString = "User ID=SYSDBA;Password=masterkey;" + "Database=localhost:C:\\Program Files\\Attend HRM\\Data\\ITAS.FDB; " + "DataSource=localhost;Charset=NONE;";
        FbConnection addDetailsConnection = new FbConnection(ConnectionString);
        addDetailsConnection.Open();
        string SQLCommandText = "Select EMP_ID,EMP_ENO from EMP_EMP where EMP_ID= '" + txtEmpId.Text + "'";
        FbDataReader dr = null;       
        //SqlDataReader dr = cmd.ExecuteReader();
        if (!dr.Read() || dr["EMP_ENO"].ToString() != txtPassword.Text)
            Response.Write("Invalid UserName&Password");
        else
            Response.Write("Valid-UserId=" + dr["PKUserId"]);

        addDetailsConnection.Close();
    }
}

I got an error this line.

C#

if (!dr.Read() || dr["EMP_ENO"].ToString() != txtPassword.Text)

Object reference not set to an instance of an object.

Posted 2-Mar-12 21:12pm

2011999

Updated 3-Mar-12 4:04am

v5

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Comments

StM0n 3-Mar-12 3:54am

Sorry... but which error do you get...

and is the gap after else in your original code?

Sergey Alexandrovich Kryukov 3-Mar-12 21:06pm

Not a question. Again.
--SA

5 solutions

Solution 1

Add the brackets that make it a method call:

C#

FbDataReader dr = addDetailsConnection.Open;

Becomes

C#

FbDataReader dr = addDetailsConnection.Open();

Posted 2-Mar-12 21:16pm

OriginalGriff

Comments

2011999 3-Mar-12 3:25am

again same Error

OriginalGriff 3-Mar-12 3:45am

And what type does Open return?
I don't think it will be a data reader of any type...

Solution 2

please try by the following :

C#

protected void txtLogin_Click(object sender, EventArgs e)
{
string ConnectionString = "User ID=SYSDBA;Password=masterkey;" + "Database=localhost:C:\\Program Files\\Attend HRM\\Data\\ITAS.FDB; " + "DataSource=localhost;Charset=NONE;";
SqlConnection cn = new SqlConnection(ConnectionString );
cn.Open();
string SQLCommandText = "Select EMP_ID,NAME

need to add PassWord fields

C#

from UserProfile where UsaeName= '" + txtEmpId.Text + "'";
 DataTable dt= new DataTable();
 sda = new SqlDataAdapter(SQLCommandText , cn);
  sda.Fill(dt);
if(dt.Rows.Count >0){
    if (dt.Rows[0]["PassWord"].ToString() != txtPassWord.Text)
Response.Write("Invalid UserName&Password");
else

Response.Write("Valid-UserId=" + dt.Rows[0]["EMP_ID"]);
}
con.Close();
}
}

Hope Be helpful,
Theingi.

Posted 2-Mar-12 21:27pm

Theingi Win

Comments

2011999 3-Mar-12 5:05am

sda = new SqlDataAdapter(SQLCommandText, ConnectionString);

Compiler Error Message: CS0103: The name 'sda' does not exist in the current context

2011999 3-Mar-12 5:13am

hear i have firebird i am using Fbdataadapter

2011999 3-Mar-12 5:13am

not using sqlData adapter

Solution 5

Apparently, dr["EMP_ENO"] returns null, and the attempt to de-reference null in ToString throws this exception. You can see it under debugger.

You should always use the debugger on a slightest concern on your run-time behavior. And certainly before asking questions like that. You could find and fix the problem much faster than posting this question and waiting for the answer.

—SA

Posted 3-Mar-12 15:10pm

Sergey Alexandrovich Kryukov

Solution 3

C#

if (!dr.Read() || dr["EMP_ENO"].ToString() != txtPassword.Text)

a little bit too early... first check

C#

if (!dr.Read())

then move to

C#

if  (dr["EMP_ENO"].ToString() != txtPassword.Text)
   Response.Write("Invalid UserName&Password");

Posted 3-Mar-12 2:03am

StM0n

Comments

2011999 3-Mar-12 8:34am

Error 1 'FirebirdSql.Data.FirebirdClient.FbConnection' does not contain a definition for 'ExecuteReader' and no extension method 'ExecuteReader' accepting a first argument of type 'FirebirdSql.Data.FirebirdClient.FbConnection' could be found (are you missing a using directive or an assembly reference?) E:\Documents and Settings\Administrator\My Documents\Visual Studio 2010\WebSites\Subbu\SelectEdit\DBdata2\EmpLeave.aspx.cs 25 49 E:\...\DBdata2\

2011999 3-Mar-12 8:35am

how to resolve it

StM0n 3-Mar-12 9:00am

Sorry, but is the code in your question correctly copied and pasted...?

And, do you have changed the .Net-Version recently?

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Martin Arapovic · Accepted Answer · 2012-03-03T02:59:00

Hi,

First, I want to comment something. You are using firebird db as I can see, so remove SQL2008 tag from question.
Second, You set your data reader to null and then you are using it... This is obviously "Object reference not set to an instance of an object" exception...

Solution...

Use FbCommand ExecuteReader method and then use reader to read returned records...

C#

string ConnectionString = "Your conn string";
FbConnection addDetailsConnection = new FbConnection(ConnectionString);
addDetailsConnection.Open();
FbCommand fbCommand = new FbCommand("Your sql command string here", addDetailsConnection);
FbDataReader fbDataReader = fbCommand.ExecuteReader();

// Add your code that uses data reader...

// And add cleanup code...
fbDataReader.Close();
addDetailsConnection.Close();

I got this Error in program

5 solutions

Solution 4

Solution 1

Solution 2

Solution 5

Solution 3

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