DOCSP-34259 re-use $expr example on find() (#6057)

* DOCSP-34259 re-use $expr example on find()

* internal review

Author: jmd-mongo

source/includes/use-expr-in-find-query.rst

@@ -0,0 +1,27 @@
+Compare Two Fields from A Single Document
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Consider a ``monthlyBudget`` collection with the following documents:
+
+.. code-block:: javascript
+
+   { "_id" : 1, "category" : "food", "budget": 400, "spent": 450 }
+   { "_id" : 2, "category" : "drinks", "budget": 100, "spent": 150 }
+   { "_id" : 3, "category" : "clothes", "budget": 100, "spent": 50 }
+   { "_id" : 4, "category" : "misc", "budget": 500, "spent": 300 }
+   { "_id" : 5, "category" : "travel", "budget": 200, "spent": 650 }
+
+The following operation uses :query:`$expr` to find documents 
+where the ``spent`` amount exceeds the ``budget``:
+
+.. code-block:: javascript
+
+   db.monthlyBudget.find( { $expr: { $gt: [ "$spent" , "$budget" ] } } )
+
+The operation returns the following results:
+
+.. code-block:: javascript
+
+   { "_id" : 1, "category" : "food", "budget" : 400, "spent" : 450 }
+   { "_id" : 2, "category" : "drinks", "budget" : 100, "spent" : 150 }
+   { "_id" : 5, "category" : "travel", "budget" : 200, "spent" : 650 }

source/reference/method/db.collection.find.txt

@@ -373,6 +373,8 @@ field does not exists:
 
 For a list of the query operators, see :ref:`query-selectors`.
 
+.. include:: /includes/use-expr-in-find-query.rst
+
 .. _query-subdocuments:
 .. _query-embedded-documents:
 

source/reference/operator/query/expr.txt

@@ -59,34 +59,7 @@ If the :pipeline:`$match` stage is part of a :pipeline:`$lookup` stage,
 Examples
 --------
 
-Compare Two Fields from A Single Document
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Consider an ``monthlyBudget`` collection with the following documents:
-
-.. code-block:: javascript
-
-   { "_id" : 1, "category" : "food", "budget": 400, "spent": 450 }
-   { "_id" : 2, "category" : "drinks", "budget": 100, "spent": 150 }
-   { "_id" : 3, "category" : "clothes", "budget": 100, "spent": 50 }
-   { "_id" : 4, "category" : "misc", "budget": 500, "spent": 300 }
-   { "_id" : 5, "category" : "travel", "budget": 200, "spent": 650 }
-
-The following operation uses :query:`$expr` to find documents 
-where the ``spent`` amount exceeds the ``budget``:
-
-.. code-block:: javascript
-
-   db.monthlyBudget.find( { $expr: { $gt: [ "$spent" , "$budget" ] } } )
-
-The operation returns the following results:
-
-.. code-block:: javascript
-
-   { "_id" : 1, "category" : "food", "budget" : 400, "spent" : 450 }
-   { "_id" : 2, "category" : "drinks", "budget" : 100, "spent" : 150 }
-   { "_id" : 5, "category" : "travel", "budget" : 200, "spent" : 650 }
-
+.. include:: /includes/use-expr-in-find-query.rst
 
 Using ``$expr`` With Conditional Statements
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~