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Null Predicate

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NexusDB V3 Manual

Null Predicate

NexusDB Manual V3 > SQL Reference > Predicates

Specify a test for a null value.

Syntax

<null predicate> ::=

<row value predicand> <null predicate part 2>

<null predicate part 2> ::= IS [ NOT ] NULL

Notes

§	The degree of the row value predicand shall be 1.

§	IS NULL evaluates to TRUE if the row value is null, else to FALSE.

§	IS NOT NULL evaluates to TRUE if the row value is different from null, else to FALSE.

Examples

1)	The following example selects students who don't take any courses:

SELECT studentID, studentName

FROM students s

left join enrolls e ON e.studentID = s.studentID

WHERE e.studentID IS NULL

Conformance

SQL:2003 standard

-

-

Core SQL

Feature F481 "Expanded NULL predicate"

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