Connection error while performing query

Question

I’m a beginner in programming and I’m trying to connect to a database. But by clicking the "Search" button to browse the database and exbir values on my screen, the following error is generated through a messagebox that I put in Catch:

""An Attempt to attach an auto-named database for file C: (path database file). A database with the same name exists, or specified file cannot be opened, or it is Located on UNC share.""

Below is my code to connect and display values:

namespace trenodb
{
    public partial class Form1 : Form
    {
        static string strDb = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=\"C:\\Users\aRtHuRz\\Documents\\Visual Studio 2015\\Projects\\trenodb\\trenodb\\dbTrenodb.mdf\";Integrated Security=True;Connect Timeout=30";

    public Form1()
    {
        InitializeComponent();
    }

    private void btnPesquisar_Click(object sender, EventArgs e)
    {
        string pesquisar = "SELECT * FROM Table WHERE [Id] = " + txtID;
        SqlConnection conexao = new SqlConnection(strDb);
        SqlCommand cmd = new SqlCommand(pesquisar, conexao);
        SqlDataReader DR;
        try
        {
            conexao.Open();
            DR = cmd.ExecuteReader();
            if (DR.Read())
            {
                txtID.Text = DR.GetValue(0).ToString();
                txtNome.Text = DR.GetValue(1).ToString();
                txtFone.Text = DR.GetValue(2).ToString();
                txtEndereço.Text = DR.GetValue(3).ToString();
                DR.Close();
            } cmd.Dispose();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        finally
        {
            conexao.Close();
        }
    }
}

}

Answer 1

I will do a step by step how to generate the connection string.

Search the Services tab.

Configure the connection string with the desired database.

Configured connection string.

Now you can copy it and use it in the location where you pass your current one, or, use by the properties of the project.

Example:

string strConexao = Integraoplogserrapark.properties.Settings.default.stringConnect;

If you notice, the thread we created in the project is right after the Default property. Thus the configured connection string is returned.