使用命令 Update-Database 时无法连接到 DATABASE

Question

So, let me explain the problem a bit. I have installed MYSQL server and created a new connection and a database MYSQL SERVER

And i can connect with no error: Connection no error

Then i used the "Server Explorer" menu in visual studio to connect to the same database and grab the connection string i will use. Server Explorer Wizard

Now i have this code:

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; }
    }
}

Driver.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": "*"
}

Inside of Startup.cs

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<>));
        }

After the command: add-migration initialmigration a new file is created (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]

So, now, i expect that using the command Update-Database a new table is created and all. But i recieve an exception 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

You're using the SqlServer initialisation code in the line:

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

However, you have stated that the database you are using is MySQL , not SqlServer , which is a different product. Therefore changing the initialisation code to UseMySQL should solve the issue:

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