The most complete definition of Select<> (and others like SelectDistinct<>) is public virtual SqlExpression<T> Select<Table1, Table2, Table3, Table4, Table5, Table6, Table7>(Expression<Func<Table1, Table2, Table3, Table4, Table5, Table6, Table7, object>> fields);
as of version 5.1.0.
Is it possible to add definitions that allows more than 7 tables to be part of the projection? (like Or<> and And<>)