Add example of graph edges existing before records exist (#1071)

src/content/doc-surrealql/statements/relate.mdx

@@ -461,6 +461,69 @@ SELECT * FROM likes;
 ]
 ```
 
+
+### Using RELATE on non-existent records
+
+As mentioned at the top of the page, `RELATE` can be used for records that do not yet exist. While this behaviour can be overridden by using the `ENFORCED` keyword, it can be useful in certain situations.
+
+For example, the `VALUE` clause inside a [`DEFINE FIELD`](/docs/surrealdb/surrealql/statements/define/field) statement is calculated every time a record is altered (that is, every time it is created or updated). If this value depends on a graph edge, creating the record first will cause `VALUE` to calculate it based on a nonexistent path.
+
+In the following example, a `house` table has a field called `has_road_access` that depends on whether any `->has_road` paths return an output that is not empty. Meanwhile, the city has a new road under construction but no houses are present and their details have not been set yet.
+
+```surql
+-- Returns true if $this->has_road path is not empty
+DEFINE FIELD has_road_access ON TABLE house VALUE !!$this->has_road->road;
+CREATE road SET name = "Dalhurst Way", length = 10.5;
+```
+
+As the addresses of the upcoming houses have been decided, the `->has_road` path can be set ahead of time by giving the `house` records an ID based on their exact address.
+
+```surql
+LET $road = SELECT * FROM ONLY road WHERE name = "Dalhurst Way" LIMIT 1;
+RELATE [
+    house:[218, "Dalhurst Way"],
+    house:[222, "Dalhurst Way"],
+    house:[226, "Dalhurst Way"],
+]->has_road->$road;
+```
+
+Later on, two new houses are completed in the city and registered in the database. As the path to `house:[218, "Dalhurst Way"]` has already been set up, the `has_road_access` field will evaluate to `true`, while the other house in the middle of nowhere will evaluate to `false`.
+
+```surql
+CREATE house:[218, "Dalhurst Way"] SET floors = 2, bedrooms = 5;
+CREATE house:[0, "Middle of nowhere"] SET floors = 4, bedrooms = 12;
+```
+
+```surql
+-------- Query --------
+
+[
+	{
+		bedrooms: 5,
+		floors: 2,
+		has_road_access: true,
+		id: house:[
+			218,
+			'Dalhurst Way'
+		]
+	}
+]
+
+-------- Query --------
+
+[
+	{
+		bedrooms: 12,
+		floors: 4,
+		has_road_access: false,
+		id: house:[
+			0,
+			'Middle of nowhere'
+		]
+	}
+]
+```
+
 ## Querying graphs
 
 ### Different ways to reach similar results