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NULL Predicate

  • Článek

The NULL predicate indicates whether the document has a value for the indicated column.

The NULL predicate has the following syntax:

...WHERE <column> IS [NOT] NULL

The optional NOT keyword negates the result. The column can be a regular or delimited identifier.

Important

To test whether a column has the NULL value, you must use the NULL predicate. It is not valid to use the NULL value in a comparison predicate. "WHERE column IS NULL" is correct. "WHERE column = NULL" is not valid.

 

Example

The following example returns documents that do not have a System.Video.Director value.

...WHERE System.Video.Director IS NULL

Reference

LIKE Predicate

Literal Value Comparison

Multi-Valued (ARRAY) Comparisons

Conceptual

Full-Text Predicates

Non-Full-Text Predicates