simp only [nrows, count, Schema.length_eq_List_length]
η : Type u_η
dec_η : DecidableEq η
sch : Schema
τ : Type
inst✝ : DecidableEq τ
t : Table sch
c : η
hc : Schema.HasCol (c, τ) sch
⊢ nrows (count t c) = List.length (List.unique (getColumn2 t c))
η : Type u_η
dec_η : DecidableEq η
sch : Schema
τ : Type
inst✝ : DecidableEq τ
t : Table sch
c : η
hc : Schema.HasCol (c, τ) sch
⊢ List.length (count.pairsToRow (List.counts (getColumn2 t c))) = List.length (List.unique (getColumn2 t c))