multiple primary keys

In CreateTable, replace the code creating the string given to the Execute method by

        var sbQuery = new StringBuilder("create table if not exists \"").Append(map.TableName).Append("\"(\n");
        map.Columns.Aggregate(sbQuery, (sb, column) => sb.Append(Orm.SqlDecl(column, StoreDateTimeAsTicks)).Append(",\n"));

        var pks = (from c in map.Columns where c.IsPK select c).ToList();
        if (pks.Count != 0)
        {
            //, PRIMARY KEY (A_ID, B_ID)
            sbQuery.Append("primary key (");
            pks.Aggregate(sbQuery, (sb, c) => sb.Append(c.Name).Append(','));
            sbQuery.Remove(sbQuery.Length - 1, 1).Append(')');
        }
        else
        {
            sbQuery.Remove(sbQuery.Length - 3, 3);
        }

        sbQuery.Append(")");
        var count = Execute(sbQuery.ToString());

And in the SqlDecl method, remove the line

decl += "primary key ";

Also in MigrateTable add a not supported exception:

        foreach (var p in toBeAdded)
        {
            if (p.IsPK)
                throw new Exception("New columns can not be primary keys (unsupported migration)");

            var addCol = "alter table \"" + map.TableName + "\" add column " + Orm.SqlDecl(p, StoreDateTimeAsTicks);
            Execute(addCol);
        }