Function is_null 

pub fn is_null<'a, V, E>(
    expr: E,
) -> SQLExpr<'a, V, <V::DialectMarker as DialectTypes>::Bool, NonNull, E::Aggregate, ScopeOnly<E::Sources>>
where
    V: SQLParam + 'a,
    E: Expr<'a, V>,

NULL check (IS NULL).

Renders expr IS NULL. Accepts any expression. The result is the dialect’s boolean and is never NULL.

Examples

assert_eq!(is_null(users.email).sql(), r#""users"."email" IS NULL"#);