I am having a problem changing the default value
for a column with C# code. The simplest way to
do it seems to be to use oleDbDataAdapter1.Fill(dt),
even though I don't actually want to query for
any data in the database? I just want a handle
to the table so I can change one of its columns
default value.

In VS, I setup a oleDbConnection1 using the
Server Explorer/Data Connections.

I just set it up with any old SQL connection
string, I'm not interested in the dataset:

this.oleDbSelectCommand1.CommandText = "SELECT *\r\nFROM table1";
this.oleDbSelectCommand1.Connection = this.oleDbConnection1;

Then, I wrote the following code:
            DataTable dt = new DataTable();
            oleDbDataAdapter1.Fill(dt);
            dt.Columns["color"].DefaultValue = "green";
            oleDbDataAdapter1.Update(dt);
            oleDbConnection1.Close();

This code doesn't work.

I'm looking at the generated code in the designer and
it makes me think that to change the default value for
a column, I should be using

System.Data.OleDb.OleDbParameter

or

oleDbDataAdapter1.TableMappings?

Any help would be appreciated.