Question

I have a table named t_Student in Microsoft SQL Server 2005 database. In that table there are three columns named student_regiNo, student_Name, student_Email.

I’m using following code segment to retrieve “student_Name”. But instead of showing “student_Name” it shows “System.Data.SqlClient.SqlDataReader”. Whats the problem?

private void GetDatabaseConnection()
{
    string connectionString = @"server=RZS-F839AD139AA\SQLEXPRESS; Integrated Security = SSPI; database = StudentCourseInformation";
    connection = new SqlConnection(connectionString);
    connection.Open();
}

public string GateStudentName(string selectedStudentRegiNo)
{
    GetDatabaseConnection();

    string selectedStudentQuery = @"SELECT student_Name FROM t_Student WHERE (
                                  student_regiNo = 
                                  '" +selectedStudentRegiNo+ @"'  
                                   )";
    SqlCommand command = new SqlCommand(selectedStudentQuery, connection);
    SqlDataReader reader = command.ExecuteReader();

    string selectedStudentName = Convert.ToString(reader);
    return selectedStudentName;
}

Answer 1

Use

return (string)command.ExecuteScalar();

as far as you have to return “the first column of the first row in the result set returned by the query” (from MSDN)

Also use parametrized query:

var command = new connection.CreateCommand()
command.CommandText = "SELECT student_Name FROM t_Student WHERE student_regiNo = @number";
command.Parameters.AddWithValue(@number, selectedStudentRegiNo);