Enum NullHandling 

pub enum NullHandling {
    Propagate,
    AbsorbsNull,
    Custom,
}

How a function handles NULL arguments.

Variants

Propagate

NULL in any argument produces NULL output.

This is standard SQL behavior for most scalar functions. Enables simplification when any argument is known to be NULL.

AbsorbsNull

NULL is short-circuited when paired with the absorbing element.

This is a special case where the absorbing element “wins” over NULL.

Examples

• AND_KLEENE(false, NULL) → false (false absorbs NULL)
• OR_KLEENE(true, NULL) → true (true absorbs NULL)

Custom

The function has special NULL semantics that don’t follow simple propagation rules.

This prevents any simplifications based on NULL arguments.

Examples

• IS NULL, IS NOT NULL: NULL → true/false
• COALESCE: returns first non-NULL argument
• NULLIF: conditionally produces NULL

Trait Implementations

impl Clone for NullHandling

fn clone(&self) -> NullHandling

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NullHandling

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for NullHandling

fn default() -> NullHandling

Returns the “default value” for a type.

impl PartialEq for NullHandling

fn eq(&self, other: &NullHandling) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for NullHandling

impl StructuralPartialEq for NullHandling