Function sign 

pub fn sign<'a, V, E>(
    expr: E,
) -> SQLExpr<'a, V, <V::DialectMarker as DialectTypes>::Double, E::Nullable, E::Aggregate>
where
    V: SQLParam + 'a,
    E: Expr<'a, V>,
    E::SQLType: Numeric,

SIGN - returns the sign of a number (-1, 0, or 1).

Returns a Double, preserves nullability.

Example

use drizzle_core::expr::sign;

// SELECT SIGN(users.balance)
let balance_sign = sign(users.balance);