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一、 操作步骤
二、编写EF模型和数据库上下文
三、 移植#xff08;Migrations#xff09;数据库
四、编写应用程序并运行 前文已经说过.NET Framework4.8 控制台应用通过EF访问新建数据库#xff0c;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#x…目录
一、 操作步骤
二、编写EF模型和数据库上下文
三、 移植Migrations数据库
四、编写应用程序并运行 前文已经说过.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。本文再说下.NET 6.0控制台应用通过EF访问新建数据库的操作过程。
一、 操作步骤 新建VS.NET Framework 6.0控制台应用安装适合版本的EF程序包7.0.14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。
//数据库上下文BloggingContext和EF模型
using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;namespace _10_13
{public class BloggingContext : DbContext{public DbSetBlog? Blogs { get; set; }public DbSetPost? Posts { get; set; }/// summary/// 数据库连接字符串数据库的名字可改可不改因为移植生成的数据库是虚拟的/// /summaryprotected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder){optionsBuilder.UseSqlServer(Server(localdb)\mssqllocaldb;DatabaseEFGetStarted.ConsoleApp.NewDb;Trusted_ConnectionTrue;);}}public class Blog{public int? BlogId { get; set; }public string? Url { get; set; }public ListPost? Posts { get; set; }}public class Post{public int? PostId { get; set; }public string? Title { get; set; }public string? Content { get; set; }public int? BlogId { get; set; }public Blog? Blog { get; set; }}
}三、 移植Migrations数据库 如果Add-Migration出现警告而失败就按下述过程操作。也可以无论是否因警告而失败都可以直接按下述操作。
//新建数据库
PM Import-Module C:\Users\YCZN_MT\.nuget\packages\microsoft.entityframeworkcore.tools\7.0.14\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-VerbVerb 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: MyMigratin
Build started...
Build succeeded.
To undo this action, use Remove-Migration.
PM Update-Database
Build started...
Build succeeded.
Applying migration 20231115035211_MyMigratin.
Failed executing DbCommand (3ms) [Parameters[], CommandTypeText, CommandTimeout30]
CREATE TABLE [Blogs] ([BlogId] int NOT NULL IDENTITY,[Url] nvarchar(max) NULL,CONSTRAINT [PK_Blogs] PRIMARY KEY ([BlogId])
);
Microsoft.Data.SqlClient.SqlException (0x80131904): There is already an object named Blogs in the database.at Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action1 wrapCloseInAction)at Microsoft.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action1 wrapCloseInAction)at Microsoft.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)at Microsoft.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean dataReady)at Microsoft.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean isAsync, Int32 timeout, Boolean asyncWrite)at Microsoft.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource1 completion, Boolean sendToPipe, Int32 timeout, Boolean usedCache, Boolean asyncWrite, Boolean inRetry, String methodName)at Microsoft.Data.SqlClient.SqlCommand.ExecuteNonQuery()at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject parameterObject)at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary2 parameterValues)at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable1 migrationCommands, IRelationalConnection connection)at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String connectionString, String contextType)at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String connectionString, String contextType)at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.c__DisplayClass0_0..ctorb__0()at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
ClientConnectionId:217d3687-28a0-4467-8dfd-09e430245bc2
Error Number:2714,State:6,Class:16
There is already an object named Blogs in the database.
PM 我的电脑中在其他项目中已经移植生成过同样的数据库因此在数据库更新时提示并警告忽略就好了不影响本项目的调试和运行的。
四、编写应用程序并运行
//.NET 6.0控制台应用EF访问新建数据库
//每运行一次增加一条记录
//同一台电脑其他项目移植过相同的项目的话在Update-Database时会
//发生可以忽略的红色警告不影响向调试运行。只要自动生成移植就可以
using System;namespace _10_13
{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);}}}
}//运行效果
/*1 records saved to databaseAll blogs in database:- http://blogs.msdn.com/adonet- http://blogs.msdn.com/adonetC:\Users\YCZN_MT\Desktop\测试1\10_13[.NET6.0控制台 EF新建]\10_13\bin\Debug\net6.0\10_13.exe (进程 12848)已退出代码为 0。
按任意键关闭此窗口. . .*/ 第一条记录是同一台电脑的另外的工程生成的数据库记录第二条记录是本项目执行1次后生成的如果关闭执行后重新执行每执行一次添加1条记录。
