Function ln 

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

LN - returns the natural logarithm of a number.

SQLite and MySQL return NULL outside the logarithm domain. PostgreSQL reports an error for invalid non-NULL input.

Example

use drizzle_core::expr::ln;

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