Update README.md

Author: bebo-dot-dev

postgres/README.md

@@ -24,6 +24,49 @@ This notifications database contains 2 tables, 1 regular function and 1 trigger
 
 1. notify_notification_changes
 
+```
+CREATE FUNCTION public.notify_notification_changes()
+    RETURNS trigger
+    LANGUAGE 'plpgsql'
+    COST 100
+    VOLATILE NOT LEAKPROOF
+AS $BODY$
+DECLARE 
+    tr_record RECORD;
+    trigger_data json;
+    notification_data json;
+BEGIN    
+    IF (TG_OP = 'DELETE') THEN
+        tr_record = OLD;        
+    ELSE
+        tr_record = NEW;        
+    END IF;
+    
+    trigger_data = row_to_json(r)
+        FROM (
+            SELECT 
+                n.*,
+                nt.name notification_type
+            FROM
+                (SELECT tr_record.*) n
+                JOIN public.notification_type nt on n.notification_type_id = nt.id
+        ) r;
+    
+    notification_data = json_build_object(
+        'table', TG_TABLE_NAME,
+        'operation', TG_OP,
+        'data', trigger_data
+	  );
+
+    PERFORM pg_notify(
+        'notifications_data_changed',
+        notification_data::text
+    );
+
+  RETURN tr_record;
+END;
+$BODY$;
+```
 
 ## function calls:
 
@@ -36,4 +79,4 @@ SELECT public.new_notification(
 
 
 ## pgadmin
-![files](./pgadmin.png)
+![files](./pgadmin.png)