Is null: isnull

Syntax

isnull ( op )

Input parameters

op	the operand

Examples of valid syntaxes

isnull(DS_1)

Semantics for scalar operations

The operator returns TRUE if the value of the operand is NULL, FALSE otherwise. For example:

isnull(“Hello”) gives FALSE

isnull(NULL) gives TRUE

Input parameters type

op

dataset {measure<scalar> _}
| component<scalar>
| scalar

Result type

result

dataset { measure<boolean> bool_var }
| component<boolean>
| boolean

Additional Constraints

If op is a Data Set then it has exactly one measure.

Behaviour

The operator has the typical behaviour of the “Operators changing the data type” (see the section “Typical behaviours of the ML Operators”).

Examples

Given the operand dataset DS_1:

Input DS_1 (see structure)

Id_1	Id_2	Id_3	Id_4	Me_1
2012	B	Total	Total	11094850
2012	G	Total	Total	11123034
2012	S	Total	Total
2012	M	Total	Total	46818219
2012	F	Total	Total	5401267
2012	W	Total	Total

Example 1

DS_r := isnull(DS_1);

results in (see structure):

DS_r

Id_1	Id_2	Id_3	Id_4	bool_var
2012	B	Total	Total	False
2012	G	Total	Total	False
2012	S	Total	Total	True
2012	M	Total	Total	False
2012	F	Total	Total	False
2012	W	Total	Total	True

Example 2

DS_r := DS_1[ calc Me_2 := isnull(Me_1) ];

results in (see structure):

DS_r

Id_1	Id_2	Id_3	Id_4	Me_1	Me_2
2012	B	Total	Total	11094850	False
2012	G	Total	Total	11123034	False
2012	S	Total	Total		True
2012	M	Total	Total	46818219	False
2012	F	Total	Total	5401267	False
2012	W	Total	Total		True