Execute scalar c#

Goran Bibic

If put in text box username (a) and password (a) app say invalid column name "a"

Line 10 problem....some help?

private void prijava()
{
SqlConnection myConnection = new SqlConnection(cs);
String command = "SELECT id FROM osobe_korisnici where korisnicko_ime = " + korisnikTextBox.Text + "";
myConnection.Open();
SqlCommand myCommand = new SqlCommand(command, myConnection);
korisnikId = Int32.Parse(myCommand.ExecuteScalar().ToString());

5 Replies

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Nitin Sontakke8y ago
Accepted answer
What is the data type of column 'korisnicko_ime'?.

If it is char / varchar / nvarchar then your query should be as follows:
private void prijava()

        {





            SqlConnection myConnection = new SqlConnection(cs);

            String command = "SELECT id FROM osobe_korisnici where korisnicko_ime = '" + korisnikTextBox.Text + "'";

            myConnection.Open();

            SqlCommand myCommand = new SqlCommand(command, myConnection);



            korisnikId = Int32.Parse(myCommand.ExecuteScalar().ToString());

And several times have I told you NOT TO use form controls directly in the query. Take their value in some other variable. Preferably pass it as a parameter to the function, or something like that. You tightly couple the UI with database access which is not quite recommended.
Goran Bibic8y ago
Solved, Thank you

' " + korisnikTextBox.Text + " ' ";

This was as problem
Nitin Sontakke8y ago
In future, whenever you have such issues, use debug, copy the contents of the variable command, paste the contents in the SQL Server Management Studio and execute.

When you see the command you will immediately notice that something is wrong there....
Nitin Sontakke8y ago
That explains. Use the piece of code I had pasted in my previous reply.
Goran Bibic8y ago
Korisnicko ime varchar (255)