NULL Predicate in SharePoint Search SQL Syntax
Applies to: SharePoint Server 2010
Indicates whether the document has a value for the specified column.
…WHERE <column> IS [NOT] NULL
Remarks
The optional NOT keyword negates the result. The column can be a regular or delimited identifier.
Note
To test whether a column has the NULL value, you must use the NULL predicate. It is not correct syntax to use the NULL value in a comparison predicate.
Correct: …WHERE column IS NULL
Incorrect:…WHERE column = NULL
Examples
The following example returns documents that have no author.
…WHERE Title IS NULL