WQL Operators

 

The Windows Management Instrumentation Query Language (WQL) supports a set of standard operators that are used in the WHERE clause of a SELECT statement, as follows.

 

Operator

Description

=

Equal to

<

Less than

>

Greater than

<=

Less than or equal to

>=

Greater than or equal to

!= or <>

Not equal to

 

There are a few additional WQL-specific operators: IS, IS NOT, ISA, and LIKE. The IS and IS NOT operators are valid in the WHERE clause only if the constant is NULL. For example, the following queries are valid:

 

SELECT * FROM Win32_LogicalDisk WHERE FileSystem IS NULL

SELECT * FROM Win32_LogicalDisk WHERE FileSystem IS NOT NULL

 

The following queries show invalid uses of IS and IS NOT:

 

SELECT * FROM Win32_LogicalDisk WHERE DriveType IS 5

SELECT * FROM Win32_LogicalDisk WHERE FileSystem IS NOT "NTFS"

 

The ISA operator is used in the WHERE clause of data and event queries to test embedded objects for a class hierarchy. The ISA operator eliminates the need for keeping track of newly-derived classes when requesting a hierarchy of classes. When you use ISA, newly-created and existing subclasses of the requested class are automatically included in the result set.

 

The LIKE operator determines whether or not a character string matches a specified pattern. The specified pattern can contain exactly the characters to match, or it can contain meta characters. The following table lists the meta characters.

 

Character

Description

[ ]

Any one character within the specified range ([a=f]) or set ([abcdef]).

^

Any one character not within the range ([^a=f]) or set ([^abcdef].)

%

Any string of 0 (zero) or more characters. The following example finds all instances where "Win" is found anywhere in the class name: SELECT * FROM meta_class WHERE __Class LIKE "%Win%"

_

(underscore)

Any one character. Any literal underscore used in the query string must be escaped by placing it inside [] (square brackets).

 

Because the underscore is a meta character, if the query target has an underscore, the "[]" escape characters must surround it. For example, you can query for all the classes that have a double underscore in the name.

 

To locate all classes with a double underscore in the name, you must escape both underscores with [] (square brackets), for example:

 

SELECT * FROM meta_class WHERE __CLASS LIKE "%[_][_]%"

 

Windows 2000 and Windows NT 4.0:  The LIKE operator is not available.

 

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