appwrite/docs/examples/1.3.x/server-dotnet/examples/databases/update-document.md

using Appwrite;
using Appwrite.Models;

var client = new Client()
    .SetEndPoint("https://cloud.appwrite.io/v1") // Your API Endpoint
    .SetProject("5df5acd0d48c2") // Your project ID
    .SetKey("919c2d18fb5d4...a2ae413da83346ad2"); // Your secret API key

var databases = new Databases(client);

Document result = await databases.UpdateDocument(
    databaseId: "[DATABASE_ID]",
    collectionId: "[COLLECTION_ID]",
    documentId: "[DOCUMENT_ID]");