How do I commit the changes I have made to a DataTable to the Table from which I grabbed it?

Question

I'm working on a minimalist database interface that grabs all relevant information from all relevant tables and stores that information in data tables locally so that the information can be modified, changed, updated, and what not, as needed without maintaining a constant connection to the database.

The method works perfectly, all changes are reflected and stored in the table, and that's great.

Now I need to know how to go about reflecting the changes made locally in the data tables to the database that I grabbed the tables from.

Everything I've read seems to me to say "You need to maintain a connection to do that" but because it may take some amount of time to enact the changes to the datatables, and I've heard it's best practice to just establish a connection, do what you need to, and then get out, I'm seeing a kind of conflict here.

The articles I'm referencing are this one , and this one .

This is the code for getting the table(s) :

public static DataTable GetTable( string Table ) {
    string Query = "SELECT * FROM " + Table;
    return SQLLib.GetDataTable( Query, null );
}

private static DataTable GetDataTable( string CMD, object[] Params ) {
    DataSet DS = new DataSet( );
    using ( MySqlConnection MSQCon = new MySqlConnection( SQLLib.sqlconstr ) ) {
        try { MSQCon.Open( ); } catch ( MySqlException ) {
            Console.WriteLine( "Failed to open SQL Connection" );
        }
        MySqlDataAdapter MSQDA = new MySqlDataAdapter( );
        MySqlCommand MSQCom = new MySqlCommand( CMD, MSQCon );

        if (Params != null) for ( int c = 0; c < Params.Length; c++ )
            MSQCom.Parameters.AddWithValue( "@param_val_" + ( c + 1 ), Params[c] );
        MSQCom.CommandType = CommandType.Text;
        MSQDA.SelectCommand = MSQCom;
        MSQDA.Fill( DS );
        MSQCon.Close( );
    } try { return DS.Tables[0];
    } catch ( IndexOutOfRangeException ) { return SQLLib.GetDataTable( CMD, Params ); }
}

So, now, is there a method through which I can update the source table with the DataTable I keep locally until it's ready to be committed?

Answer 1

It is not about keeping the connection open, you just have to use the Command Builder, it's the same with MySql I believe.

private MySqlDataAdapter adapt;
private DataSet someDataSet;
someDataSet = new DataSet();

    public DataSet GetCustomerData(int customerId)
    {
        using(MySqlConnection connect = new MySqlConnection(ConnString))
        {
            connect.Open();
            MySqlCommand comm = new MySqlCommand("SELECT * FROM customers WHERE Id = @0", connect);
            someDataSet.Tables.Add("CustomersTable");
            comm.Parameters.AddWithValue("@0", customerId);
            adapt.SelectCommand = comm;
            adapt.Fill(someDataSet.Tables["CustomersTable"]);
        }

        return someDataSet;
   }

Now for the updating: you could use a new adapter as well, but then you have to give it a select command, based on that the commandbuilder will make the Insert,Update and Delete commands.

    public void UpdateTable(DataTable table, int customerId)
    {
        using (MySqlConnection connect = new MySqlConnection(ConnString))
        {
            connect.Open();
            MySqlCommandBuilder commbuilder = new MySqlCommandBuilder(adapt);
            adapt.SelectCommand = new MySqlCommand("SELECT * FROM customers WHERE Id = "+customerId, connect); //or use parameters.addwithvalue
            adapt.Update(table);
        }
    }

Answer 2

You should create a MySqlCommand for updating your database and set it as your MySqlDataAdapter 's UpdateCommand property value. Exactly as you do this for the SelectCommand .

When you are ready to commit, you just call the Update() method of your MySqlDataAdapter .