Improve Delete CRUD section and exercises

- Added introductory explanations for delete operations
- Added examples using deleteOne() and deleteMany()
- Improved delete challenge instructions and hints
- Refined filter and variable naming for better readability
- Added MongoDB documentation links with UTM tracking
- Added explanations about DeleteResult and deleted document counts

Author: ricardohsmello

java/40_delete.ipynb

@@ -13,8 +13,13 @@
    "id": "3b936925-e295-489a-b508-2b99c0160217",
    "metadata": {},
    "source": [
-    "# CRUD: Delete\n",
-    "    "
+    "# Basic CRUD: Delete\n",
+    "\n",
+    "## What can the `delete` operation do?\n",
+    "\n",
+    "The [`delete`](https://www.mongodb.com/docs/drivers/java/sync/current/crud/delete/?utm_campaign=devrel&utm_source=third-part-content&utm_medium=cta&utm_content=crud-operations-java-workshop&utm_term=ricardo.mello) operations let us remove documents from a MongoDB collection.\n",
+    "\n",
+    "In this section, we will use operations such as `deleteOne()` and `deleteMany()` to remove documents from the `books` collection."
    ]
   },
   {
@@ -54,6 +59,10 @@
     "\n",
     "import java.util.List;\n",
     "\n",
+    "// Configure SLF4J Simple Logger to suppress MongoDB driver logs in the notebook output.\n",
+    "System.setProperty(\"org.slf4j.simpleLogger.defaultLogLevel\", \"off\");\n",
+    "System.setProperty(\"org.slf4j.simpleLogger.log.org.mongodb.driver\", \"off\");\n",
+    "\n",
     "// Set your connection String\n",
     "String connectionString = \"mongodb://admin:mongodb@localhost:27017/\";\n",
     "\n",
@@ -77,7 +86,7 @@
    "source": [
     "## Insert one book\n",
     "\n",
-    "We want to make sure this book is in the collection, so we can later delete it."
+    "We want to make sure this book exists in the collection so we can later remove it using a delete operation."
    ]
   },
   {
@@ -91,12 +100,10 @@
    },
    "outputs": [],
    "source": [
-    "Document platero = new Document();\n",
-    "\n",
-    "platero\n",
-    "    .append(\"_id\", \"platero\")\n",
-    "    .append(\"title\", \"Platero y yo\")\n",
-    "    .append(\"year\", 1900);\n",
+    "Document platero = new Document()\n",
+    "        .append(\"_id\", \"platero\")\n",
+    "        .append(\"title\", \"Platero y yo\")\n",
+    "        .append(\"year\", 1900);\n",
     "\n",
     "books.insertOne(platero);"
    ]
@@ -106,7 +113,9 @@
    "id": "9f6caab3",
    "metadata": {},
    "source": [
-    "### We find the document we just inserted using the `_id` field"
+    "### Find the inserted book\n",
+    "\n",
+    "In this example, we query the `books` collection using the `_id` field to confirm that the `Platero y yo` document exists before deleting it."
    ]
   },
   {
@@ -131,7 +140,11 @@
    "id": "worth-windows",
    "metadata": {},
    "source": [
-    "### Delete that book"
+    "### Delete one book\n",
+    "\n",
+    "In this example, we use `deleteOne()` to remove the document with `_id` equal to `\"platero\"` from the `books` collection. \n",
+    "\n",
+    "The returned `DeleteResult` lets us verify how many documents were deleted."
    ]
   },
   {
@@ -145,12 +158,13 @@
    },
    "outputs": [],
    "source": [
-    "Document bookFrom1500 = new Document(\"year\", 1500);\n",
+    "Document plateroFilter = new Document(\"_id\", \"platero\");\n",
     "\n",
-    "DeleteResult deleteResult = books.deleteOne(new Document(\"_id\", \"platero\"));\n",
+    "DeleteResult deleteResult = books.deleteOne(plateroFilter);\n",
     "\n",
     "// Check the number of deleted documents\n",
     "long deletedCount = deleteResult.getDeletedCount();\n",
+    "\n",
     "System.out.println(\"Deleted \" + deletedCount + \" document(s).\");"
    ]
   },
@@ -169,6 +183,10 @@
    "source": [
     "### Delete all the reviews for bookId \"0786222727\" through a single command.\n",
     "\n",
+    "\n",
+    "_Hint: You may need an operation capable of deleting multiple documents at once._\n",
+    "\n",
+    "\n",
     "[Solution here](https://mongodb-developer.github.io/sql-to-query-api-lab/docs/CRUD/INSERT-DELETE#-2-delete-all-the-reviews-for-bookid-0786222727-through-a-single-command)"
    ]
   },
@@ -183,7 +201,27 @@
    },
    "outputs": [],
    "source": [
-    "// type your code here\n"
+    "//TYPE YOUR CODE HERE\n",
+    "\n",
+    "MongoCollection<Document> reviews = library.getCollection(\"reviews\");\n",
+    "\n",
+    "Bson filter = <REPLACE_WITH_FILTER>;\n",
+    "\n",
+    "DeleteResult result = <REPLACE_WITH_DELETE_OPERATION>;\n",
+    "\n",
+    "System.out.println(result.getDeletedCount() + \" reviews deleted.\");"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "7920a719",
+   "metadata": {},
+   "source": [
+    "## Summary\n",
+    "\n",
+    "In this section, we learned how to remove documents from MongoDB using operations such as `deleteOne()` and `deleteMany()`.\n",
+    "\n",
+    "We also explored how to verify deleted documents before removal and how to use `DeleteResult` to confirm how many documents were deleted."
    ]
   }
  ],