在SQL Server 2008上设置实体框架代码第一个数据库 [英] Setting up a Entity Framework Code First Database on SQL Server 2008

问题描述

我使用SQL Server CE成功创建了我的第一个实体框架代码第一个项目。数据库表是自动创建的，一切都很好。

I successfully created my first Entity Framework Code first project using SQL Server CE. The database tables were created automatically and all was well.

然后我更改了我的连接字符串，指向我创建的SQL Server数据库，并预期它会自动生成表。没有，而是抱怨表不存在。

I then changed my connection string to point to a SQL Server database I'd created and expected it to autogenerate the tables. It didn't and instead complained about the tables not existing.

经过阅读后，我发现我需要添加一个初始化程序到我的 App_Start 方法。

After some reading I found that I needed to add an initializer to my App_Start method.

我试过：

// Method 1
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<EFContext>());

但是最初没有工作，因为它找不到EdmMetaData表来发现是否模型已经改变。

But this didn't work at first because it couldn't find an EdmMetaData table to discover if the model had changed.

所以我尝试添加：

// Method 2
Database.SetInitializer(new CreateDatabaseIfNotExists<EFContext>());

但这没有工作，因为我已经创建了数据库，当我删除数据库它仍然没有工作，因为我没有创建数据库权限登录的用户。

But this didn't work because I'd already created the database, and when I removed the database it still didn't work because the user I was logging in as didn't have create database privileges.

我终于尝试了：

// Method 3
Database.SetInitializer(new DropCreateDatabaseAlways<EFContext>());

哪个工作，但我不想每次都丢弃db。所以一旦运行并添加了EdmMetaData表，我用方法1替换它，现在工作正常。

Which worked, but I don't really want to drop the db every time. So once it ran and added the EdmMetaData table I replaced it with method 1 and that now works fine.

尽管这种方法有效，但它并不像以前那样优雅我使用的是SQL Server CE，我还没有发现有人建议您使用这种方法。

Although this method works, it doesn't feel as elegant as when I was using SQL Server CE and I've not found someone suggesting that you use this method.

所以，我错过了一些更简单，更优雅的方式

So, am I missing something and is there an easier, more elegant way to do this?

推荐答案

方法1和2希望数据库不存在。如果您手动创建数据库，它们不起作用。如果您需要EF在现有数据库中创建表，则必须创建自定义数据库初始化程序。

Method 1 and 2 expects that database doesn't exist yet. They don't work if you create database manually. If you need EF to create tables in existing database you must create custom database initializer.

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