NULL Predicate
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
Related topics
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Reference
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Conceptual
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