使用命令 Update-Database 时无法连接到 DATABASE

Question

所以，让我稍微解释一下这个问题。 我已经安装了 MYSQL 服务器并创建了一个新的连接和一个数据库 MYSQL SERVER

我可以毫无错误地连接： Connection no error

然后我使用 Visual Studio 中的“服务器资源管理器”菜单连接到同一个数据库并获取我将使用的连接字符串。 Server Explorer Wizard

现在我有了这个代码：

DataRepository.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using TranscoopTrips.Data.Interfaces;

namespace TranscoopTrips.Data
{
    public class DataRepository<T> : IDataRepository<T> where T : class
    {
        private readonly DriverContext _context;

        public DataRepository(DriverContext context)
        {
            _context = context;
        }

        public void Add(T entity)
        {
            _context.Set<T>().Add(entity);
        }

        public void Update(T entity)
        {
            _context.Set<T>().Update(entity);
        }

        public void Delete(T entity)
        {
            _context.Set<T>().Remove(entity);
        }

        public async Task<T> SaveAsync(T entity)
        {
            await _context.SaveChangesAsync();
            return entity;
        }
    }
}

DriverContext.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using ApplicazioneAutotrasporti.Model;

namespace TranscoopTrips.Data
{
    public class DriverContext : DbContext
    {
        public DriverContext (DbContextOptions<DriverContext> options)
            : base(options)
        {
        }

        public DbSet<ApplicazioneAutotrasporti.Model.Driver> Driver { get; set; }
    }
}

驱动程序.cs

using ApplicazioneAutotrasporti.Model.interfaces;
using System.ComponentModel.DataAnnotations;

namespace ApplicazioneAutotrasporti.Model
{
    public class Driver : IDriver
    {
        [Key]
        public int id { get; set; }
        [Required]
        public string name { get; set; }
        [Required]
        public string surname { get; set; }
    }
}

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "ConnectionStrings": {
    "DriverContext": "server=127.0.0.1;user id=root;persistsecurityinfo=True;database=transcooptrips"
  },
  "AllowedHosts": "*"
}

Startup.cs 内部

public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();
            services.AddDbContext<DriverContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DriverContext")));
            // In production, the Angular files will be served from this directory
            services.AddSpaStaticFiles(configuration =>
            {
                configuration.RootPath = "ClientApp/dist";
            });
            services.AddScoped(typeof(IDataRepository<>), typeof(DataRepository<>));
        }

命令后：add-migration initialmigration 创建一个新文件 (XXXX_initialmigration.cs)

[using Microsoft.EntityFrameworkCore.Migrations;

    namespace TranscoopTrips.Migrations
    {
        public partial class initialmigration : Migration
        {
            protected override void Up(MigrationBuilder migrationBuilder)
            {
                migrationBuilder.CreateTable(
                    name: "Driver",
                    columns: table => new
                    {
                        id = table.Column<int>(nullable: false)
                            .Annotation("SqlServer:Identity", "1, 1"),
                        name = table.Column<string>(nullable: false),
                        surname = table.Column<string>(nullable: false)
                    },
                    constraints: table =>
                    {
                        table.PrimaryKey("PK_Driver", x => x.id);
                    });
            }

            protected override void Down(MigrationBuilder migrationBuilder)
            {
                migrationBuilder.DropTable(
                    name: "Driver");
            }
        }
    }][4]

所以，现在，我希望使用命令 Update-Database 创建一个新表。但我收到一个例外 Exception

PM> update-database
Build started...
Build succeeded.
Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
 ---> System.ComponentModel.Win32Exception (2): The system cannot find the file specified.
   at Microsoft.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling, String accessToken, DbConnectionPool pool, SqlAuthenticationProviderManager sqlAuthProviderManager)
   at Microsoft.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at Microsoft.Data.SqlClient.SqlConnection.Open()
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.<>c__DisplayClass18_0.<Exists>b__0(DateTime giveUp)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.<>c__DisplayClass12_0`2.<Execute>b__0(DbContext c, TState s)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation, Func`2 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists(Boolean retryOnNotExists)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
ClientConnectionId:00000000-0000-0000-0000-000000000000
Error Number:2,State:0,Class:20
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)

Answer 1

您正在使用该行中的 SqlServer 初始化代码：

services.AddDbContext<DriverContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DriverContext")));

但是，您已声明您使用的数据库是 MySQL，而不是 SqlServer，后者是不同的产品。因此将初始化代码更改为UseMySQL 应该可以解决问题：

services.AddDbContext<DriverContext>(options => options.UseMySQL(Configuration.GetConnectionString("DriverContext")));