Umbraco-CMS/src/Umbraco.Infrastructure/Persistence/SqlServerDatabaseCreator.cs

using System;
using System.Data.SqlClient;
using System.IO;
using Umbraco.Cms.Core;

namespace Umbraco.Cms.Infrastructure.Persistence
{
    public class SqlServerDatabaseCreator : IDatabaseCreator
    {
        public string ProviderName => Constants.DatabaseProviders.SqlServer;

        public void Create(string connectionString)
        {
            var builder = new SqlConnectionStringBuilder(connectionString);

            // Get connection string without database specific information
            var masterBuilder = new SqlConnectionStringBuilder(builder.ConnectionString)
            {
                AttachDBFilename = string.Empty,
                InitialCatalog = string.Empty
            };
            var masterConnectionString = masterBuilder.ConnectionString;

            string fileName = builder.AttachDBFilename,
                database = builder.InitialCatalog;

            // Create database
            if (!string.IsNullOrEmpty(fileName) && !File.Exists(fileName))
            {
                if (string.IsNullOrWhiteSpace(database))
                {
                    // Use a temporary database name
                    database = "Umbraco-" + Guid.NewGuid();
                }

                using var connection = new SqlConnection(masterConnectionString);
                connection.Open();

                using var command = new SqlCommand(
                    $"CREATE DATABASE [{database}] ON (NAME='{database}', FILENAME='{fileName}');" +
                    $"ALTER DATABASE [{database}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE;" +
                    $"EXEC sp_detach_db @dbname='{database}';",
                    connection);
                command.ExecuteNonQuery();

                connection.Close();
            }
            else if (!string.IsNullOrEmpty(database))
            {
                using var connection = new SqlConnection(masterConnectionString);
                connection.Open();

                using var command = new SqlCommand(
                    $"IF NOT EXISTS (SELECT * FROM sys.databases WHERE name = '{database}') " +
                    $"CREATE DATABASE [{database}];",
                    connection);
                command.ExecuteNonQuery();

                connection.Close();
            }
        }
    }
}