I'm trying to learn how to use SQL in C#.

I ran into an issue and I can't figure it out. I made a ComboBox which reads data from my database and uses the database's Id as a ValueMember and displays a title.

I want to use the selected title's Id, so I can write the contents of a row to a RichTextBox with the click of a button.

So if I have selected the first title in the combobox, which has Id 1 in the database, I want to use that info to show the corresponding text in the richtextbox. I thought I figured it out, but it gives me an error:

String was not in correct format

The database is very simple:

Here's my code:

        private void LoadData()
        {
            using (Connection = new SqlConnection(ConnectionString)) //Make the connection
            using (Adapter = new SqlDataAdapter("SELECT Title FROM StoryTable", ConnectionString))
            {
                Connection.Open();
                DataTable TitleTable = new DataTable(); 
                Adapter.Fill(TitleTable);
                SelectionBox.ValueMember = "Id"; 
                SelectionBox.DisplayMember = "Title";
                SelectionBox.DataSource = TitleTable;
            }          
        }

        private void LoadButton_Click(object sender, EventArgs e)
        {
            int Id = Int32.Parse(SelectionBox.ValueMember); //String was not in correct format...
            using (Connection = new SqlConnection(ConnectionString))
            using (Adapter = new SqlDataAdapter("SELECT Story FROM StoryTable", ConnectionString))
            {
                Connection.Open();
                var TextTable = new DataSet();
                Adapter.Fill(TextTable);
                StoryTextbox.Text = TextTable.Tables[0].Rows[Id]["Story"].ToString();
            }
        }

CodePudding user response：

The immediate problem is that this:

int Id = Int32.Parse(SelectionBox.ValueMember);

should be this:

int Id = (int)SelectionBox.SelectedValue;

Actually, I just realised that there's another problem. You do this:

SelectionBox.ValueMember = "Id"; 
SelectionBox.DisplayMember = "Title";

yet this is your query:

SELECT Title FROM StoryTable

How are you going to bind the Id column when you're not even retrieving it?

SELECT Id, Title FROM StoryTable