Function ln 

pub fn ln<'a, V, E>(expr: E) -> SQLExpr<'a, V, Double, E::Nullable, Scalar>
where
    V: SQLParam + 'a,
    E: Expr<'a, V>,
    E::SQLType: Numeric,

LN - returns the natural logarithm of a number.

Returns Double type, preserves nullability.

Example

use drizzle_core::expr::ln;

// SELECT LN(users.value)
let natural_log = ln(users.value);