Update PostgreSQL-Integration.md

give another way to generate database

docs/en/Best-Practices/PostgreSQL-Integration.md

@@ -15,26 +15,59 @@
 - Update to use PostgreSQL in `XXXMigrationsDbContextFactory`
   - Replace the `new DbContextOptionsBuilder<XXXMigrationsDbContext>().UseSqlServer()` with the `new DbContextOptionsBuilder<XXXMigrationsDbContext>().UseNpgsql()`
 
-#### Delete Existing Migrations
+### Delete Existing Migrations
 
 Delete all existing migration files (including `DbContextModelSnapshot`)
 
 ![postgresql-delete-initial-migrations](images/postgresql-delete-initial-migrations.png)
 
-#### Regenerate Initial Migration & Update the Database
+### Regenerate Initial Migration
 
-Set the correct startup project (usually a web project),
-Open the **Package Manager Console** (Tools -> Nuget Package Manager -> Package Manager Console), select the `Acme.BookStore.EntityFrameworkCore.DbMigrations` as the **Default project** and execute the following command:
+Set the correct startup project (usually a web project)
+
+![set-as-startup-project](../images/set-as-startup-project.png)
+
+Open the **Package Manager Console** (Tools -> Nuget Package Manager -> Package Manager Console), select the `.EntityFrameworkCore.DbMigrations` as the **Default project** and execute the following command:
 
 Run `Add-Migration` command.
 ````
 PM> Add-Migration Initial
 ````
 
-Then execute the `Update-Database` command to update the database schema:
+### Update the Database
+
+You have two options to create the database.
+
+#### Using the DbMigrator Application
+
+The solution contains a console application (named `Acme.BookStore.DbMigrator` in this sample) that can create database, apply migrations and seed initial data. It is useful on development as well as on production environment.
+
+> `.DbMigrator` project has its own `appsettings.json`. So, if you have changed the connection string above, you should also change this one.
+
+Right click to the `.DbMigrator` project and select **Set as StartUp Project**:
+
+![set-as-startup-project](../images/set-as-startup-project.png)
+
+Hit F5 (or Ctrl+F5) to run the application. It will have an output like shown below:
+
+![set-as-startup-project](../images/db-migrator-app.png)
+
+#### Using EF Core Update-Database Command
+
+Ef Core has `Update-Database` command which creates database if necessary and applies pending migrations.
+
+Set the correct startup project (usually a web project)
+
+![set-as-startup-project](../images/set-as-startup-project.png)
+
+Open the **Package Manager Console** (Tools -> Nuget Package Manager -> Package Manager Console), select the `.EntityFrameworkCore.DbMigrations` as the **Default project** and execute the following command:
 
 ````
 PM> Update-Database
 ````
 
+This will create a new database based on the configured connection string.
+
 ![postgresql-update-database](images/postgresql-update-database.png)
+
+> Using the `.DbMigrator` tool is the suggested way, because it also seeds the initial data to be able to properly run the web application.