Question

I am trying to save data to a database on a button push, but the variables seem to be private by the nature of where they are defined. I have tried to move where they are defined, but this seems to produce other errors.

Given a fix, why was it fixed that way?

The code follows.

namespace enable {     public partial class Form1 : Form     {         public Form1()         {             InitializeComponent();             OleDbConnection favouriteConnection = new System.Data.OleDb.OleDbConnection('Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\\\\192.168.123.5\\Share\\Matt\\BugTypes.mdb');             string strSQL = 'SELECT CategoryName, Show ' + 'FROM [Categories] WHERE Show = 'Yes' ' + 'ORDER BY CategoryName';             OleDbDataAdapter adapter = new OleDbDataAdapter(strSQL, favouriteConnection);             OleDbCommandBuilder cBuilder = new OleDbCommandBuilder(adapter);             DataTable dTable = new DataTable();             adapter.Fill(dTable);             BindingSource bSource = new BindingSource();             bSource.DataSource = dTable;             dataGridView1.DataSource = bSource;             adapter.Update(dTable);         }         private void button1_Click(object sender, EventArgs e)         {             adapter.Update(dTable);//this is the button that needs to do the save, but can't see the variables.         }     } } 

Answer 1

You’re declaring dTable and adapter in the constructor, so it goes out of scope as soon as the constructor is completed.

You want to move the variable declarations out into the main class, like:

public partial class Form1 : Form {     private DataTable dTable;     private OleDbDataAdapter adapter;      Public Form1()     {          ... your setup here ...          dTable = new DataTable();          ... etc ...     } }