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john rob

Total Post:108

Posted on    January-28-2014 12:12 AM

 C# C# 

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I am trying to create a select statement in C# to check if the value inserted into a textbox (userName) is in an existing SQL database. I have a database called Employee containing a table called EVUSERS and it has a column called UName.

In my code I have a method which takes the value from a textbox called UserBox. I would like to know if there is a temporary table where the select is stored which I can compare the textbox value to.

Here is the code:

private void CheckLoginExist()


            String userName = UserBox.Text;

            string connectionString = @"Data Source=.\SQLEXPRESS;Database=Employee;Integrated Security=true";

            using (SqlConnection connection = new SqlConnection(connectionString))


                using (SqlCommand command = connection.CreateCommand())


                    command.CommandText = "SELECT UName FROM EVUSERS WHERE UName = @UName";

                    command.Parameters.AddWithValue("@UName", userName);







Pravesh Singh

Total Post:411

Posted on    January-28-2014 12:55 AM

Hi John,

You need ExecuteScalar, not ExecuteNonQuery


var name = command.ExecuteScaclar().ToString();


if (name != null) {

  MessageBox.Show("This name already exists");



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