Question

I have .mdb database, and code like this:

using (OleDbConnection connection = new OleDbConnection(myConnectionString))
{
    using (OleDbCommand cmd = connection.CreateCommand())
    {
        cmd.CommandText = "UPDATE myTab SET col2 = @val1 WHERE col1 = @val2";
        cmd.Parameters.AddWithValue("@val1", 0);
        cmd.Parameters.AddWithValue("@val2", -1);
        cmd.Connection.Open();
        cmd.ExecuteNonQuery();
        cmd.Connection.Close();
     }
}

I get data from db, change it in my gui programm, then save it in db. Changes saves, but not in db (I don’t know where), so when I run program, change data, close program, then again run – changes remain, but when I open db (not in programm), there are no changes saved, and again run – all changes disappear.
PS: when I commit changes, then run program several times, all changes disappear too, after (3-4 runs)

Answer 1

When we we add .mdb in project root in VS ,when change structure ,VS default delete .mdb file in debug folder and replace new file; now you can change this defult :

1- right click .mdb file and select option

2- set Copy To Output Directory to Do Not Copy