How Can I Solve This Exception? The Result Of The Expression Is Always 'False' Since A Value Of Type 'Int' Is Never Equal To 'Null' Of Type "Int"

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protected void Button1_Click(object sender, EventArgs e)
    {<pre>String conn = "Data Source = (LocalDB)\\v11.0;AttachDbFilename = C:\\Users\\Abudlkader\\Documents\\My_Site.mdf;Integrated Security = True;Connect Timeout = 30";
        SqlConnection myconn = new SqlConnection(conn);
        myconn.Open();
        String Query = "SELECT ID FROM SH_SignUp_SignIn WHERE E-Mail LIKE" + TextBox2.Text + "'AND Password LIKE'" + TextBox1.Text + "'";
        SqlCommand mycomm = new SqlCommand();
        mycomm.Connection = myconn;
        mycomm.CommandText = Query;
        int x = Convert.ToInt16(mycomm.ExecuteScalar());
        if (x == null)
        {
            Response.Redirect("~//Default5.aspx");
        }
        else
        {
            Response.Redirect("~//Default4.aspx");
        }
        myconn.Close();
    }
}</pre>

Posted 20-Dec-14 9:11am

Hamza Attal

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Maciej Los · Answer 1 · 2014-12-20T09:35:00

This:

C#

String Query = "SELECT ID FROM SH_SignUp_SignIn WHERE E-Mail LIKE" + TextBox2.Text + "'AND Password LIKE'" + TextBox1.Text + "'";

is going to:

SQL

SELECT ID FROM SH_SignUp_SignIn WHERE E-Mail LIKETextBox2_Text'AND Password LIKE'TextBox1_Text'

and should be:

SQL

SELECT ID FROM SH_SignUp_SignIn WHERE E-Mail = 'TextBox2_Text' AND Password = 'TextBox1_Text'

Got it?

PIEBALDconsult · Answer 2 · 2014-12-20T10:13:00

Solution 2

Change
int x = Convert.ToInt16(mycomm.ExecuteScalar());
to
object x = mycomm.ExecuteScalar();

Posted 20-Dec-14 10:13am

PIEBALDconsult

SK Yadav · Answer 3 · 2014-12-20T17:28:00

you can change int x to some string variable as you are using int to just check whether some ID exists in DB or not. try using like this:

C#

string x = Convert.ToString(mycomm.ExecuteScalar());
        if (x == DBNull.Value)
        {
            Response.Redirect("~//Default5.aspx");
        }
        else
        {
            Response.Redirect("~//Default4.aspx");
        }

Hope this helps.

How Can I Solve This Exception? The Result Of The Expression Is Always 'False' Since A Value Of Type 'Int' Is Never Equal To 'Null' Of Type "Int"

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