如何检查 LocalDB 中的数据库创建是否完成

Question

我在一个项目中使用 SQL 服务器作为数据库以及 Entity Framework Core 3.1。对于单元测试/集成测试，我们使用 LocalDB。

为确保 LocalDB 数据库处于正确的迁移状态，我们删除并重新创建测试数据库。

看起来像这样：

using (var sqlConnection = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Integrated Security=True"))
{
    sqlConnection.Open();

    new SqlCommand("USE MASTER", sqlConnection).ExecuteNonQuery();

    try
    {
        new SqlCommand($"ALTER DATABASE [MyTestDb] SET SINGLE_USER WITH ROLLBACK IMMEDIATE", sqlConnection).ExecuteNonQuery();
        new SqlCommand($"DROP DATABASE [MyTestDb]", sqlConnection).ExecuteNonQuery();
    }
    catch (SqlException e)
    {
        // We get an error if there is no database. This happens the very first time a test gets executed on a machine
    }

    new SqlCommand($"CREATE DATABASE [MyTestDb];", sqlConnection).ExecuteNonQuery();
    new SqlCommand($"ALTER DATABASE [MyTestDb] SET ALLOW_SNAPSHOT_ISOLATION ON;", sqlConnection).ExecuteNonQuery();
    new SqlCommand($"ALTER DATABASE [MyTestDb] SET READ_COMMITTED_SNAPSHOT  ON;", sqlConnection).ExecuteNonQuery();
}

using (var creationConnection = new SqlConnection(@$"Data Source=(localdb)\MSSQLLocalDB;Integrated Security=True;Initial Catalog=MyTestDb"))
{
    creationConnection.Open(); // <-- Problematic exception here

    using (var context = new MyDbContext(/*some DbContextOptions here... */))
    {
        context.Database.Migrate();
    }
}

这将在 creationConnection.Open(); 上引发异常并显示以下消息：

Microsoft.Data.SqlClient.SqlException (0x80131904): Cannot open database "MyTestDb" requested by the login. The login failed.
Login failed for user ''.

如果我在两个 using 块之间添加一个 Thread.Sleep(10_000);，则不会抛出异常。

using (var sqlConnection = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Integrated Security=True"))
{
    sqlConnection.Open();

    new SqlCommand("USE MASTER", sqlConnection).ExecuteNonQuery();

    try
    {
        new SqlCommand($"ALTER DATABASE [MyTestDb] SET SINGLE_USER WITH ROLLBACK IMMEDIATE", sqlConnection).ExecuteNonQuery();
        new SqlCommand($"DROP DATABASE [MyTestDb]", sqlConnection).ExecuteNonQuery();
    }
    catch (SqlException e)
    {
        // We get an error if there is no Database. This happens the very first time a test gets executed on a machine
    }

    new SqlCommand($"CREATE DATABASE [MyTestDb];", sqlConnection).ExecuteNonQuery();
    new SqlCommand($"ALTER DATABASE [MyTestDb] SET ALLOW_SNAPSHOT_ISOLATION ON;", sqlConnection).ExecuteNonQuery();
    new SqlCommand($"ALTER DATABASE [MyTestDb] SET READ_COMMITTED_SNAPSHOT  ON;", sqlConnection).ExecuteNonQuery();
}

Thread.Sleep(10_000); // <-- exception will NOT be thrown 

using (var creationConnection = new SqlConnection(@$"Data Source=(localdb)\MSSQLLocalDB;Integrated Security=True;Initial Catalog=MyTestDb"))
{
    creationConnection.Open(); 

    using (var context = new MyDbContext(/*some DbContextOptions here... */))
    {
        context.Database.Migrate();
    }
}

我假设数据库 MyTestDb 未在 creationConnection.Open(); 就绪并抛出错误。

有没有办法检查数据库创建是否完成？

Answer 1

你可以这样做：

SELECT [collation_name] FROM sys.databases WHERE name = 'MyTestDb';

如果collation_name有值（不为空），则数据库在线。

如何检查 LocalDB 中的数据库创建是否完成

How to check if database creation in LocalDB is finished

c#

sql-server

unit-testing

localdb

ef-core-3.1