Added C# tabs and solutions to challenge answers

docs/40-CRUD/2-SELECT.mdx

@@ -88,7 +88,7 @@ Here:
 
         await cursor.forEach((b) => {
             console.log(b);
-        });      
+        });
         ```
       </div>
 
@@ -100,6 +100,27 @@ Here:
         ```
       </div>
     </TabItem>
+     <TabItem value="csharp" label="C#">
+      <div>
+        ```csharp
+       var projection = Builders<Book>.Projection.Include(b => b.Title).Exclude(b => b.Id);
+
+      var booksWithOnlyTitle = booksCollection.Find(b => true).Project<Book>(projection).Limit(50).ToList();
+
+      if(booksWithOnlyTitle != null)
+      {
+          foreach(var book in booksWithOnlyTitle)
+          {
+            Console.WriteLine(book.ToJson()); // Shows the entire BSON document as JSON to show that some fields are null because they are not returned due to the projection
+          }
+      }
+      else
+      {
+          Console.WriteLine("Empty Collection");
+      }
+        ```
+      </div>
+    </TabItem>
   </Tabs>
 </details>
 
@@ -126,5 +147,28 @@ Here:
           ```
         </div>
     </TabItem>
+     <TabItem value="csharp" label="C#">
+      <div>
+        ```csharp
+          var historyGenre = Builders<Book>.Filter.AnyEq(b => b.Genres, "History");
+          var projection = Builders<Book>.Projection.Exclude(b => b.Id).Exclude(b => b.Authors);
+
+          List<Book> sortedBooks = booksCollection.Find(historyGenre)
+            .Project<Book>(projection).Limit(50).ToList();
+
+          if(sortedBooks != null)
+          {
+              foreach(var book in sortedBooks)
+              {
+                Console.WriteLine(book.ToJson()); // Shows the entire BSON document as JSON to show that some fields are null because they are not returned due to the projection
+              }
+          }
+          else
+          {
+            Console.WriteLine("Empty Collection");
+          }
+```
+      </div>
+    </TabItem>
   </Tabs>
 </details>

docs/40-CRUD/3-ORDER-LIMIT.mdx

@@ -86,5 +86,18 @@ This returns the **top 10 available books** in the "Science Fiction" genre.
         ```
       </div>
     </TabItem>
+    <TabItem value="csharp" label="C#">
+      <div>
+        ```csharp
+        var projection = Builders<Book>.Projection.Include(b => b.Title).Include(b => b.Pages);
+        var ascendingTitleSort = Builders<Book>.Sort.Ascending("title");
+
+        List<Book> topBooks = booksCollection.Find(b => true) // Empty filter to find all books
+          .Project<Book>(projection)
+          .Sort(ascendingTitleSort)
+          .Limit(10).ToList();
+        ```
+      </div>
+    </TabItem>
   </Tabs>
 </details>

docs/40-CRUD/4-INSERT-DELETE.mdx

@@ -135,7 +135,22 @@ DELETE FROM reviews WHERE bookId = '0786222727';
             ]);
             ```
           </div>
-    </TabItem>
+      </TabItem>
+      <TabItem value="csharp" label="C#">
+          <div>
+            ```csharp
+           var newReviews = new[]
+            {
+                new Review { Text = "Thrilling end.", Rating = 4, Name = "Mark", BookId = "0786222727" },
+                new Review { Text = "Must read!", Rating = 5, Name = "Raj",  BookId = "0786222727" },
+                new Review { Text = "Very expensive", Rating = 3, Name = "Yun",  BookId = "0786222727" },
+                new Review { Text = "Extremely satisfied with the storyline!", Rating = 5, Name = "Lisa", BookId = "0786222727" }
+            };
+
+            reviewsCollection.InsertMany(newReviews);
+            ```
+          </div>
+      </TabItem>
   </Tabs>
 </details>
 
@@ -159,5 +174,16 @@ DELETE FROM reviews WHERE bookId = '0786222727';
             ```
           </div>
     </TabItem>
+    <TabItem value="csharp" label="C#">
+      <div>
+      ```csharp
+      IMongoCollection<Review> reviewsCollection = db.GetCollection<Review>("reviews");
+
+      var deletionResult = reviewsCollection.DeleteMany(r => r.BookId == "0786222727");
+
+      Console.WriteLine($"{deletionResult.DeletedCount} review(s) deleted.");
+      ```
+      </div>
+    </TabItem>
   </Tabs>
 </details>

docs/40-CRUD/5-UPDATE.mdx

@@ -90,7 +90,7 @@ Executing the above command will insert a fresh new document in the collection,
       <div>
           ```js
           await books.updateOne(
-            {"title": "Treasure of the Sun"}, 
+            {"title": "Treasure of the Sun"},
             {$set: {pages: 449}}
           );
           ```
@@ -100,11 +100,24 @@ Executing the above command will insert a fresh new document in the collection,
           <div>
             ```js
             db.books.updateOne(
-              {"title": "Treasure of the Sun"}, 
+              {"title": "Treasure of the Sun"},
               {$set: {pages: 449}}
             );
             ```
           </div>
     </TabItem>
+     <TabItem value="csharp" label="C#">
+          <div>
+            ```csharp
+            var filter = Builders<Book>.Filter.Eq(b => b.Title, "Treasure of the Sun");
+            var update = Builders<Book>.Update.Set(b => b.Pages, 449);
+
+            var result = booksCollection.UpdateOne(filter, update);
+
+            // Optionally inspect the outcome
+            Console.WriteLine($"Matched: {result.MatchedCount}, Modified: {result.ModifiedCount}");
+            ```
+          </div>
+    </TabItem>
   </Tabs>
 </details>

docs/50-aggregation/2-match-project.mdx

@@ -118,6 +118,28 @@ db.books.aggregate([
             ```
           </div>
     </TabItem>
+     <TabItem value="csharp" label="C#">
+        <div>
+        ```csharp
+            var pipeline = booksCollection.Aggregate()
+              .Match(b => b.Available > 2);
+
+            var plentifulBooks = pipeline.ToList();
+
+            if(plentifulBooks != null)
+            {
+              foreach(var book in plentifulBooks)
+              {
+                Console.WriteLine($"Title: {book.Title} - Available: {book.Available}");
+              }
+            }
+            else
+            {
+              Console.WriteLine("Empty Collection");
+            }
+        ```
+      </div>
+    </TabItem>
   </Tabs>
 </details>
 
@@ -146,5 +168,28 @@ db.books.aggregate([
         ```
       </div>
     </TabItem>
+     <TabItem value="csharp" label="C#">
+        <div>
+        ```csharp
+          var pipeline = booksCollection.Aggregate()
+              .Match(b => b.Available > 2)
+              .Project(b => new { b.Title, b.Year });
+
+          var plentifulBooks = pipeline.ToList();
+
+          if(plentifulBooks != null)
+          {
+            foreach(var book in plentifulBooks)
+            {
+              Console.WriteLine($"Title: {book.Title} - Year: {book.Year}");
+            }
+          }
+          else
+          {
+            Console.WriteLine("Empty Collection");
+          }
+        ```
+      </div>
+    </TabItem>
   </Tabs>
 </details>

docs/50-aggregation/3-sort-limit.mdx

@@ -77,67 +77,114 @@ SELECT * FROM books ORDER BY timestamp DESC LIMIT 5;
 <details>
   <summary>Answer</summary>
   <div>
-  There are 2 ways to solve this- 
+  There are 2 ways to solve this-
   - $project
   - $addFields
 
 :::info
 Learn [when to use $addFields over $project](https://www.practical-mongodb-aggregations.com/guides/project.html?highlight=%24project#when-to-use-project)
 :::
 
-  <Tabs groupId="aggregations">
-    <TabItem value="mongodb-shell" label="Using $project">
-      ```js
-     await books.aggregate([
-  {
-    $match: { year: { $gt: 2000 } }
-  },
-  {
-    $match: {
-      authors: { $exists: true }
-    }
-  },
-  {
-    $project: {
-      title: 1,
-      year: 1,
-      authors: 1,
-      numAuthors: { $size: "$authors" }
-    }
-  },
-  {
-    $sort: { numAuthors: -1 }
-  },
-  {
-    $limit: 1
-  }
-]).toArray();
-      ```
+  <Tabs groupId="aggregations" defaultValue="js">
+    <TabItem value="js" label="JavaScript">
+      <Tabs groupId="js-inner" defaultValue="project">
+        <TabItem value="project" label="Using $project">
+          ```js
+          await books.aggregate([
+          {
+            $match: { year: { $gt: 2000 } }
+          },
+          {
+            $match: {
+              authors: { $exists: true }
+            }
+          },
+          {
+            $project: {
+              title: 1,
+              year: 1,
+              authors: 1,
+              numAuthors: { $size: "$authors" }
+            }
+          },
+          {
+            $sort: { numAuthors: -1 }
+          },
+          {
+            $limit: 1
+          }
+        ]).toArray();
+          ```
+        </TabItem>
+
+        <TabItem value="addFields" label="Using $addFields">
+          ```js
+          await books.aggregate([
+            {
+              $match: { year: { $gt: 2000 } }
+            },
+            {
+              $match: {
+                authors: { $exists: true },
+              }
+            },
+            {
+              $addFields: {
+                numAuthors: { $size: "$authors" },
+              }
+            },
+            {
+              $sort: { "numAuthors": -1 }
+            },
+            {
+              $limit: 1
+            }
+          ]).toArray();
+          ```
+        </TabItem>
+      </Tabs>
     </TabItem>
-    <TabItem value="atlas" label="Using $addFields">
-    ```js
-    await books.aggregate([
-      {
-        $match: { year: { $gt: 2000 } }
-      },
-      {
-        $match: {
-          authors: { $exists: true },
-        }
-      },
-      {
-        $addFields: {
-          numAuthors: { $size: "$authors" },
-        }
-      },
-      {
-        $sort: { "numAuthors": -1 }
-      },
-      {
-        $limit: 1
-      }
-    ]).toArray();
-    ```
+
+    <TabItem value="csharp" label="C#">
+      <Tabs groupId="aggregations-csharp" defaultValue="addFields">
+        <TabItem value="project" label="Using $project">
+          <div>
+          ```csharp
+          var pipeline = booksCollection.Aggregate()
+            .Match(b => b.Year > 2000)
+            .Match(Builders<Book>.Filter.Exists(b => b.Authors))
+            .Project(new BsonDocument
+            {
+                { "title", 1 },
+                { "year", 1 },
+                { "authors", 1 },
+                { "numAuthors", new BsonDocument("$size", "$authors") }
+            })
+            .Sort(new BsonDocument("numAuthors", -1))
+            .Limit(1);
+
+          var mostAuthors = await pipeline.ToListAsync();
+        ```
+          </div>
+        </TabItem>
+
+        <TabItem value="addFields" label="Using $addFields">
+          <div>
+          ```csharp
+            var pipeline = booksCollection.Aggregate()
+              .Match(b => b.Year > 2000)
+              .Match(Builders<Book>.Filter.Exists(b => b.Authors))
+              .AppendStage<BsonDocument>(
+              new BsonDocument("$addFields", new BsonDocument("numAuthors", new BsonDocument("$size", "$authors")))
+            )
+              .Sort(new BsonDocument("numAuthors", -1))
+              .Limit(1);
+
+            var mostAuthors = pipeline.ToList();
+        ```
+          </div>
+        </TabItem>
+      </Tabs>
     </TabItem>
   </Tabs>
   </div>