NULL-related functions and operators

The Null constant

Function	HTSQL	SQL	Javascript	Python
The NULL constant	null()	value is NULL	null	None

Signature: htsql:null() -> Untyped

In Javascript, there are two constants of null-ish kind: null and undefined.

Check if the value is NULL

Function	HTSQL	SQL	Javascript	Python
Check if the value is NULL	is_null(value)	value IS NULL	value === null	value is None
Check if the value is not NULL	!is_null(value)	value IS NOT NULL	value !== null	value is not None

Signature: htsql:is_null(Any value) -> Boolean

Type resolution: htsql:is_null(Untyped => String)

The function is_null(value) is equivalent to the expression value == null() (but not to value = null() as it will always produce NULL).

Note that in Javascript, value == null is also true if value is undefined.

Return non-NULL argument

Function	HTSQL	SQL	Javascript	Python
Return the first non-NULL argument	coalesce(value1, value2, ...)	COALESCE(value1, value2, ...)	--	--

Signature: htsql:coalesce(Any value1, Any value2[, ...]) -> Any

Type resolution: Every arguments must be of the same common type or be Untyped. All Untyped arguments are resolved to the common type. At least one non-Untyped argument should be present.