Question

C# (.NET 3.5)

I have an SQLite database with two tables – employees (the first column being id INTEGER PRIMARY KEY), and holidays (id INTEGER – meaning the ID of the employee; start DATE, end DATE – self-explanatory).

My form contains textboxes, checkboxes etc. to represent the employee details – but say I’d also like a list box, listing all the holidays for the currently selected employee.

So I need a data relation, as the list box is supposed to display only holidays one person at the time (IDs on both datatables needs to match).

        var command = new SQLiteCommand("SELECT * FROM employees; SELECT * FROM holidays");
        var connection=new SQLiteConnection(@"data source=C:\employees.db");
        command.Connection = connection;
        SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
        DataSet d = new DataSet();
        adapter.Fill(d);                        

        DataTable employees = d.Tables[0];

        // [...]
        // here I'm databinding my textboxes etc. to various columns 
        // of the employees data table - this works fine, navigation works well etc.
        // [...]

        DataTable holidays = d.Tables[1];            

        DataRelation relation;
        DataColumn master = employees.Columns[0];
        DataColumn slave = holidays.Columns[0];
        relation = new DataRelation("relation", master, slave);
        d.Relations.Add(relation);

        var dsView = holidays.DefaultView;
        listBox1.DisplayMember = "holidays.relation.start"; // <= it wouldn't look good like that of course, but I just want to get the thing to work for now
        listBox1.DataSource = dsView;

• but all I get is a listbox filled up with a bunch of “System.Data.DataRow”
  In this implementation, I tried to follow the tutorial I found on Akadia… Where do I go wrong? Thanks

Answer 1

First of all, you have named variables employees and holidays, but that does mean the tables within the dataset have names changed; they are still set to the default names, which, in your case are table and table1. (They would normally be table, table1 … tableN)
That means that your display member property should be as follows:

listBox1.DisplayMember = "table.relation.start";

Also, make sure you databind to the dataset itself rather than the holiday table within the dataset as follows:

listBox1.DataSource = d;

With these two changes, you should find that it works; this.BindingContext should help in navigating the parent records as you will notice only 1 set of child (holiday) results are shown at at time.

Complete modified code as follows:

    var command = new SQLiteCommand("SELECT * FROM employees; SELECT * FROM holidays");
    var connection=new SQLiteConnection(@"data source=C:\employees.db");
    command.Connection = connection;
    SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
    DataSet d = new DataSet();
    adapter.Fill(d);                        

    DataTable employees = d.Tables[0];

    // [...]
    // here I'm databinding my textboxes etc. to various columns 
    // of the employees data table - this works fine, navigation works well etc.
    // [...]

    DataTable holidays = d.Tables[1];

    DataRelation relation;
    DataColumn master = employees.Columns["id"];
    DataColumn slave = holidays.Columns["employeeid"];
    relation = new DataRelation("relation", master, slave);
    d.Relations.Add(relation);


    listBox1.DisplayMember = "table.relation.start"; // <= it wouldn't look good like that of course, but I just want to get the thing to work for now
    listBox1.DataSource = d;