apply Schema.get_map_nths_eq_get_get
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
ns : List (Fin (ncols t))
i : Nat
hi : i < List.length ns
⊢ List.get (Schema.names (Schema.nths sch ns))
      { val := i, isLt := (_ : i < List.length (header (selectColumns2 t ns))) } =
    List.get (Schema.names sch)
      { val := (List.get ns { val := i, isLt := hi }).val,
        isLt := (_ : (List.get ns { val := i, isLt := hi }).val < List.length (header t)) }
no goals