Azure Digital Twins query language reference: WHERE clause
This document contains reference information on the WHERE clause for the Azure Digital Twins query language.
The WHERE clause is the last part of a query. It's used to filter the items that are returned based on specific conditions.
This clause is optional while querying.
Core syntax: WHERE
The WHERE clause is used along with a Boolean condition to filter query results.
A condition can be a function that evaluates to a Boolean result. You can also create your own Boolean statement using the properties of twins and relationships (accessed with
.) with a comparison or contains-type operator.
With properties and operators:
--SELECT ... --FROM ... WHERE <twin-or-relationship-collection>.<property> <operator> <value-to-compare>
With a function:
--SELECT ... --FROM ... WHERE <function-with-Boolean-result>
A condition evaluating to a
Here's an example using properties and operators. The following query specifies in the WHERE clause to only return the twin with a
$dtId value of Room1.
SELECT * FROM DIGITALTWINS T WHERE T.$dtId = 'Room1'
Here's an example using a function. The following query uses the
IS_OF_MODEL function to specify in the WHERE clause to only return the twins with a model of
dtmi:sample:Room;1. For more about the
IS_OF_MODEL function, see Azure Digital Twins query language reference: Functions.
SELECT * FROM DIGITALTWINS WHERE IS_OF_MODEL('dtmi:sample:Room;1')