目录
前文已经说过.NET Framework4.8 控制台应用通过EF访问已经建立的数据库，这里说的已经建立的数据库指的是已经建立的SQLServer那样的数据库或VS 的本地数据库(localdb) \MSSQLLocalDB。这些数据库能够通过SSMS建立连接或在VS上建立本地的数据库连接，是可以操作的、可以看得见的。
本文想说的是，.NET Framework4.8 控制台应用通过EF访问新建数据库，这里的数据据库要根据事先编写好的EF模型、经过一番操作，移植（Migrations）出来的。这个数据库是看不到这个数据库的连接的。
一、 操作步骤
- 新建VS.NET Framework4.8 控制台应用；
- 安装适合版本的EF程序包，3.1.32.0；
- 编写EF模型和数据库上下文，文件录入格式是添加新的类；
- 移植（Migrations）数据库，资源管理器里生成Migrations夹；
- 编写应用程序文件Program.cs；
- 运行；
步骤1和步骤2作者以前的文章都讲过，不再重复叙述。
二、编写EF模型和数据库上下文
添加→新建项目→类，复制粘贴以下全文，一定要保证所有.cs文件在同一片空间下（namespace）。
//EF模型数据库上下文
using Microsoft.EntityFrameworkCore.Migrations;
namespace _10_10.Migrations
{
public partial class MyMigration : Migration
{
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.CreateTable(
name: "Blogs",
columns: table => new
{
BlogId = table.Column<int>(nullable: false)
.Annotation("SqlServer:Identity", "1, 1"),
Url = table.Column<string>(nullable: true)
},
constraints: table =>
{
table.PrimaryKey("PK_Blogs", x => x.BlogId);
});
migrationBuilder.CreateTable(
name: "Posts",
columns: table => new
{
PostId = table.Column<int>(nullable: false)
.Annotation("SqlServer:Identity", "1, 1"),
Title = table.Column<string>(nullable: true),
Content = table.Column<string>(nullable: true),
BlogId = table.Column<int>(nullable: false)
},
constraints: table =>
{
table.PrimaryKey("PK_Posts", x => x.PostId);
table.ForeignKey(
name: "FK_Posts_Blogs_BlogId",
column: x => x.BlogId,
principalTable: "Blogs",
principalColumn: "BlogId",
onDelete: ReferentialAction.Cascade);
});
migrationBuilder.CreateIndex(
name: "IX_Posts_BlogId",
table: "Posts",
column: "BlogId");
}
protected override void Down(MigrationBuilder migrationBuilder)
{
migrationBuilder.DropTable(
name: "Posts");
migrationBuilder.DropTable(
name: "Blogs");
}
}
}
三、 移植（Migrations）数据库
如果Add-Migration出现警告而失败，就按下属过程操作。
//移植（Migrations）数据库
PM> Import-Module C:\Users\pc\.nuget\packages\microsoft.entityframeworkcore.tools\3.1.32\tools\EntityFrameworkCore.psd1
模块“EntityFrameworkCore”中的某些导入命令的名称包含未批准的动词，这些动词可能导致这些命令名不易被发现。若要查找具有未批准的动词的命令，请使用 Verbose 参数再次运行 Import-Module 命令。有关批准的动词列表，请键入 Get-Verb。
PM> Get-Verb
Verb Group
---- -----
Add Common
Clear Common
Close Common
Copy Common
Enter Common
Exit Common
Find Common
Format Common
Get Common
Hide Common
Join Common
Lock Common
Move Common
New Common
Open Common
Optimize Common
Pop Common
Push Common
Redo Common
Remove Common
Rename Common
Reset Common
Resize Common
Search Common
Select Common
Set Common
Show Common
Skip Common
Split Common
Step Common
Switch Common
Undo Common
Unlock Common
Watch Common
Backup Data
Checkpoint Data
Compare Data
Compress Data
Convert Data
ConvertFrom Data
ConvertTo Data
Dismount Data
Edit Data
Expand Data
Export Data
Group Data
Import Data
Initialize Data
Limit Data
Merge Data
Mount Data
Out Data
Publish Data
Restore Data
Save Data
Sync Data
Unpublish Data
Update Data
Approve Lifecycle
Assert Lifecycle
Complete Lifecycle
Confirm Lifecycle
Deny Lifecycle
Disable Lifecycle
Enable Lifecycle
Install Lifecycle
Invoke Lifecycle
Register Lifecycle
Request Lifecycle
Restart Lifecycle
Resume Lifecycle
Start Lifecycle
Stop Lifecycle
Submit Lifecycle
Suspend Lifecycle
Uninstall Lifecycle
Unregister Lifecycle
Wait Lifecycle
Debug Diagnostic
Measure Diagnostic
Ping Diagnostic
Repair Diagnostic
Resolve Diagnostic
Test Diagnostic
Trace Diagnostic
Connect Communications
Disconnect Communications
Read Communications
Receive Communications
Send Communications
Write Communications
Block Security
Grant Security
Protect Security
Revoke Security
Unblock Security
Unprotect Security
Use Other
PM> Add-Migration
位于命令管道位置 1 的 cmdlet Add-Migration
请为以下参数提供值:
Name: MyMigration
Build started...
Build succeeded.
To undo this action, use Remove-Migration.
PM> Update-Database
Build started...
Build succeeded.
Applying migration '20231114142239_MyMigration'.
Done.
PM> 四、编写应用程序并运行
//.NET Framework4.8控制台应用通过EF访问新建数据库
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace _10_10
{
internal class Program
{
static void Main(string[] args)
{
using (var db = new BloggingContext())
{
db.Blogs.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
var count = db.SaveChanges();
Console.WriteLine("{0} records saved to database", count);
Console.WriteLine();
Console.WriteLine("All blogs in database:");
foreach (var blog in db.Blogs)
{
Console.WriteLine(" - {0}", blog.Url);
}
}
}
}
}//运行结果：
/*
1 records saved to database
All blogs in database:
- http://blogs.msdn.com/adonet
请按任意键继续. . .*/