Model compatibility cannot be checked because the database does not contain model metadata

使用EF的時候映射數據的時候，出現了下面的問題。如圖：

錯誤的提示爲：Model compatibility cannot be checked because the database does not contain model metadata.Model compatibility can only be checked for databases created using Code First or Code First Migrations.

解決方法：

USE [master]
GO

/****** Object: Database [DBname] ******/
 ALTER DATABASE [DBname] SET SINGLE_USER WITH ROLLBACK IMMEDIATE
 ALTER DATABASE [DBname] SET SINGLE_USER WITH NO_WAIT
 DROP DATABASE [DBname]
 GO

DBname 即爲你的數據庫名稱，執行完上面的這段Sql語句，上面出現的問題就解決了。