EF Core 無法將數據從舊數據庫傳輸到新 SQL Server 數據庫中

Question

重現步驟

我有一個 ASP.Net Core 2.2 Web 應用程序，后端 SQL Server DB 是在本教程中的 Entity Framework Core 中制作的。 https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/migrations?view=aspnetcore-2.2

總結一下步驟。

1. 下載鏈接中的項目。

2. 轉到appsettings.json 。

3. 將連接字符串中的數據庫名稱更改為ContosoUniversity2 。

4. 保存更改並構建項目。

5. 確保沒有程序實例正在運行並使用 CLI（命令行界面）或 PMC（包管理控制台）並導航到項目文件夾並輸入此命令。 dotnet ef migrations add InitialCreate 。

6. 現在輸入命令dotnet ef database update 。

預期行為

實體框架將數據從以前名為 ContosoUniversity1 的數據庫遷移到 ContosoUniversity2，包括所有列和表。 它在 Visual Studio 2019 中為作者工作。

實際行為

我只看到所有表和列的創建。 除了 __EFMigrationsHistory 中只有一行用於遷移歷史記錄之外，沒有其他數據。 我從 CLI 得到這個輸出。

`Build started...
Build succeeded.
info: Microsoft.EntityFrameworkCore.Infrastructure[10403]
      Entity Framework Core 2.2.6-servicing-10079 initialized 'SchoolContext' us
ing provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (666ms) [Parameters=[], CommandType='Text', CommandTime
out='60']
      CREATE DATABASE [ContosoUniversity2];
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (161ms) [Parameters=[], CommandType='Text', CommandTime
out='60']
      IF SERVERPROPERTY('EngineEdition') <> 5
      BEGIN
          ALTER DATABASE [ContosoUniversity2] SET READ_COMMITTED_SNAPSHOT ON;
      END;
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (18ms) [Parameters=[], CommandType='Text', CommandTimeo
ut='30']
      CREATE TABLE [__EFMigrationsHistory] (
          [MigrationId] nvarchar(150) NOT NULL,
          [ProductVersion] nvarchar(32) NOT NULL,
          CONSTRAINT [PK___EFMigrationsHistory] PRIMARY KEY ([MigrationId])
      );
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (3ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      SELECT OBJECT_ID(N'[__EFMigrationsHistory]');
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      SELECT [MigrationId], [ProductVersion]
      FROM [__EFMigrationsHistory]
      ORDER BY [MigrationId];
info: Microsoft.EntityFrameworkCore.Migrations[20402]
      Applying migration '20191227004521_InitialCreate'.
Applying migration '20191227004521_InitialCreate'.
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (2ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      CREATE TABLE [Course] (
          [CourseID] int NOT NULL,
          [Title] nvarchar(max) NULL,
          [Credits] int NOT NULL,
          CONSTRAINT [PK_Course] PRIMARY KEY ([CourseID])
      );
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (2ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      CREATE TABLE [Student] (
          [ID] int NOT NULL IDENTITY,
          [LastName] nvarchar(max) NULL,
          [FirstMidName] nvarchar(max) NULL,
          [EnrollmentDate] datetime2 NOT NULL,
          CONSTRAINT [PK_Student] PRIMARY KEY ([ID])
      );
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (3ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      CREATE TABLE [Enrollment] (
          [EnrollmentID] int NOT NULL IDENTITY,
          [CourseID] int NOT NULL,
          [StudentID] int NOT NULL,
          [Grade] int NULL,
          CONSTRAINT [PK_Enrollment] PRIMARY KEY ([EnrollmentID]),
          CONSTRAINT [FK_Enrollment_Course_CourseID] FOREIGN KEY ([CourseID]) RE
FERENCES [Course] ([CourseID]) ON DELETE CASCADE,
          CONSTRAINT [FK_Enrollment_Student_StudentID] FOREIGN KEY ([StudentID])
 REFERENCES [Student] ([ID]) ON DELETE CASCADE
      );
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      CREATE INDEX [IX_Enrollment_CourseID] ON [Enrollment] ([CourseID]);
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      CREATE INDEX [IX_Enrollment_StudentID] ON [Enrollment] ([StudentID]);
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (2ms) [Parameters=[], CommandType='Text', CommandTimeou
t='30']
      INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion])
      VALUES (N'20191227004521_InitialCreate', N'2.2.6-servicing-10079');
Done.`

環境數據：

.NET Core SDK (reflecting any global.json):
 Version:   2.2

Runtime Environment:
 OS Name:     Windows
 OS Version:  6.1.7601
 OS Platform: Windows
 RID:         win7-x64

Answer 1

遷移沒有任何問題。 解決方案是在我的備份文件夾中恢復到以前的備份，然后復制並粘貼教程中的代碼，而不是手寫。 結果我只拼錯了一行，並且能夠更正。