Function count_all 

pub fn count_all<'a, V>() -> SQLExpr<'a, V, BigInt, NonNull, Agg>
where
    V: SQLParam + 'a,

COUNT(*) - counts all rows.

Returns a BigInt, NonNull (count is never NULL), Aggregate expression.

Example

use drizzle_core::expr::count_all;

let total = count_all();
// Generates: COUNT(*)