Question

I have a Customer table –> CustomerNumber and CustomerName columns

I have a Sales table –> CustomerName columns

I have a Label (represent CustomerNumber) and a DropDownList (represent CustomerName)

I getting to DropDownList Sales table –> CustomerName with SqlDataSource.

I want automaticly (with AutoPostBack) filling Label with CustomerNumber which CustomerName selected in DropDownList

Example SQL:

select A.CustomerNumber
from Customer A, Sales B
where B.CustomerName = DropDownList1.SelectedItems.Value

I’m thinking like this.

How can i do that?

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

Answer 1

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)

{

 string selectedName = DropDownList1.SelectedValue;

 string sqlQuery = "select A.CustomerNumber from Customer A, Sales B where B.CustomerName = '" + DropDownList1.SelectedValue + "'";
 // pass you sql query to command object and call execute scalar method
 label1.Text = dbCommand.ExecuteScalar().ToString();

}

What do ExecuteScalar do?