place of a database file that can be use in ado.net

plz see thic code,i want to open(objConnection.Open();) and close a database file in this codes,but i dont know where should i place the database file(in this codes:pubs)to work.plz help me

      public partial class Form1 : Form
      {
     SqlConnection objConnection = new SqlConnection(
 "server=localhost;database=pubs;" +
 "user id=sa;password=");
    SqlDataAdapter objDataAdapter = new SqlDataAdapter();
    DataSet objDataSet = new DataSet();
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        // Set the SelectCommand properties... 
        objDataAdapter.SelectCommand = new SqlCommand();
        objDataAdapter.SelectCommand.Connection =
              objConnection;
        objDataAdapter.SelectCommand.CommandText =
         "SELECT au_lname, au_fname, title, price " +
         "FROM authors " +
        "JOIN titleauthor ON authors.开发者_开发技巧au_id = " +
        "titleauthor.au_id " +
         "JOIN titles ON titleauthor.title_id = " +
        "titles.title_id " +
         "ORDER BY au_lname, au_fname";
        objDataAdapter.SelectCommand.CommandType =
             CommandType.Text;
        // Open the database connection... 
        objConnection.Open();
        // Fill the DataSet object with data... 
        objDataAdapter.Fill(objDataSet, "authors");
        // Close the database connection... 
        objConnection.Close(); 


    }
}

If I understand you correctly, you are trying to open a SQL Server database but getting an error (let me know if that isn't the case). Under that assumption, I can say that your connection string is wrong. You have:

     SqlConnection objConnection = new SqlConnection( "server=localhost;database=pubs;user id=sa;password=");

You need to replace the "database" keyword with a keyword called "Initial Catalog", as follows:

     SqlConnection objConnection = new SqlConnection( "server=localhost;Initial Catalog=pubs;user id=sa;password=");

Let me know if this isn't what you're after.