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.

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.

For more information about the syntax and use of this operator, see the following topics:

• ISA Operator for Data Queries
• ISA Operator for Event Queries
• ISA Operator for Schema Queries

The LIKE operator is valid in the WHERE clause and is used to determine whether a given character string matches a specified pattern. For example, the following query returns all instances of Win32_ classes.

SELECT * FROM Meta_Class WHERE __Class LIKE %Win32%

For more information about the syntax and use of this operator, see LIKE Operator.

Send comments about this topic to Microsoft

Build date: 6/15/2009