add migrations info

Author: Cephas Lin

README.md

@@ -18,7 +18,7 @@ description: "A sample application you can use to follow along with Tutorial: De
 # Deploy an ASP.NET Core web app with SQL Database in Azure
 
 This is an ASP.NET Core application that you can use to follow along with the tutorial at 
-[Tutorial: Deploy an ASP.NET Core and Azure SQL Database app to Azure App Service](https://learn.microsoft.com/azure/app-service/tutorial-dotnetcore-sqldb-app) or by using the [Azure Developer CLI (azd)](https://learn.microsoft.com/azure/developer/azure-developer-cli/overview) according to the instructions below. 
+[Tutorial: Deploy an ASP.NET Core and Azure SQL Database app to Azure App Service](https://learn.microsoft.com/azure/app-service/tutorial-dotnetcore-sqldb-app) or by using the [Azure Developer CLI (azd)](https://learn.microsoft.com/azure/developer/azure-developer-cli/overview) according to the instructions below.
 
 ## Run the sample
 
@@ -39,7 +39,7 @@ This project has a [dev container configuration](.devcontainer/), which makes it
 
 ## Quick deploy
 
-This project is designed to work well with the [Azure Developer CLI](https://learn.microsoft.com/azure/developer/azure-developer-cli/overview), which makes it easier to develop apps locally, deploy them to Azure, and monitor them. 
+This project is designed to work well with the [Azure Developer CLI](https://learn.microsoft.com/azure/developer/azure-developer-cli/overview), which makes it easier to develop apps locally, deploy them to Azure, and monitor them.
 
 🎥 Watch a deployment of the code in [this screencast](https://www.youtube.com/watch?v=JDlZ4TgPKYc).
 
@@ -67,7 +67,16 @@ In the GitHub codespace:
     azd deploy
     ```
 
+## How is database migrations automated?
+
+The [AZD template](infra/resources.bicep) in this repo secures the database in a virtual network through a private endpoint. The web app can access the database through the private endpoint because it's integrated with the virtual network. In this architecture, the simplest way to do database migrations is directly from within the web app itself.
+
+Because the Linux .NET container in App Service doesn't come with the .NET SDK, you cannot run the migrations command `dotnet ef database update` easily. However, you can upload a [self-contained migrations bundle](https://learn.microsoft.com/ef/core/managing-schemas/migrations/applying?tabs=dotnet-core-cli#bundles). This repo automates the deployment of the migrations bundle as follows:
+
+- In [azure.yaml](azure.yaml), use the `prepackage` hook to generate a *migrationsbundle* file with `dotnet ef migrations bundle`.
+- In the [.csproj](DotNretCoreSqlDb.csproj) file, include the generated *migrationsbundle* file. During the `azd package` stage, *migrationsbundle* will be added to the deploy package.
+- In [infra/resources.bicep](infra/resources.bicep), add the `appCommandLine` property to the web app to run the uploaded *migrationsbundle*.
+
 ## Getting help
 
 If you're working with this project and running into issues, please post in [Issues](/issues).
-## Getting started