ASP.NET

1. Provide a web service for each website. So one website can use other website's web service to get data
2. Use a centralized database which each website uses. You can just query on this DB to get latest updates.

// use some meaningful names
string connectionString = ConfigurationManager.AppSettings["conn"];

// use parameterized queries to avoid SQL injection
// query altered to avoid unnecessary looping
string query = "select * from appointment where DATE >= @StartDate and DATE <= @EndDate";

// wrap the connection and command in using block to avoid resource leaks.
using(OleDbConnection connection = new OleDbConnection(connectionString))
using(OleDbCommand command = new OleDbCommand(query, connection);
{
    command.Parameters.AddWithValue("@StartDate", selectedDate.ToShortDateString());
    command.Parameters.AddWithValue("@EndDate", selectedDate.AddDays(7).ToShortDateString());

    connection.Open();
    // using a reader. You don't need a dataset as you are not persisting it in memory
    using(OleDbDataReader reader = command.ExecuteReader())
    {
        GridView1.DataSource = reader;
        GridView1.DataBind();        
    }
    connection.Close();
}

Mycroft Holmes wrote:

but I want the user to be able to link a cell in a datagrid or a text control to a cell in an excel spreadsheet.

Mycroft Holmes wrote:

Actually I want to configure a web form so when I click a button the form will go get the data in the cells from the xls and populate the form.

rummer wrote:

Dear Sir