MySQL"建立与 SQL Server 的连接时发生网络相关或特定于实例的错误"

Question

我一直在寻找解决这个问题的方法，唯一可能提供解决方案的解决方案是我没有尝试过的唯一解决方案，因为它涉及更改系统属性。如果可以的话，我想避免这种情况。

连接字符串正确，但仍无法连接。

异常发生在第 30 行，这是打开连接字符串的位置。conn.Open()

这是代码：

using System.Text;
using System.Data.SqlClient;
namespace My_Sql_Program
{
class Program
{
static void Main()
{
try
{
// Step 1: Create a SqlConnection Object to connect to the 
// SQL Northwind database.
SqlConnection conn = new SqlConnection("server=localhost;database=dcim;uid=root;pwd=LlmD62jL");
// Step 2: Create a SqlCommand object.
SqlCommand cmd = conn.CreateCommand();
// Step 3: Set the CommandText property of the SqlCommand object to a 
// SQL SELECT statment that retrieves a row from the Customers table.
cmd.CommandText = "SELECT UserName, UserPassword, AuthorityLevel, " +
"FROM Users " +
"WHERE UserName = 'ben'";
// Step 4: Open the database connection using the 
// Open() method of the SqlConnection object.
conn.Open();
//Step 5: Create a SqlDataReader object and call the ExecuteReader()
//Method of the SqlCommand object to run the SELECT statement.
SqlDataReader rdr = cmd.ExecuteReader();
// Step 6: Read the row from the SqlDataReader object using the Read() method.
rdr.Read();
// Step 7: Display the column values.
Console.WriteLine("rdr["UserName"] = " + rdr["UserName"]);
Console.WriteLine("rdr["UserPassword"] = " + rdr["UserPassword"]);
Console.WriteLine("rdr["AuthorityLevel"] = " + rdr["AuthorityLevel"]);
// Step 8: Close the SqlReader object using the Close() method.
rdr.Close();
// Step9: Close the SqlConnection object using the Close() method.
conn.Close();
}
catch (SqlException e) 
{
Console.WriteLine("An SqlException was thrown.");
Console.WriteLine("Number = " + e.Number);
Console.WriteLine("Message = " + e.Message);
Console.WriteLine("StackTrace:n" + e.StackTrace);
}
Console.ReadLine();
}
}
}

当我运行它时，大约 30 秒没有任何反应，然后打印SqlException：

An SqlException was thrown.
Number = 2
Message = 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)
StackTrace:
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean
breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean
breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj,
Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds
connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean
trustServerCert, Boolean integratedSecurity, Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String
newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout,
Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String
newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString
connectionOptions, SqlCredential credential, TimeoutTimer timeout)
at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout,
SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString
newSecurePassword, Boolean redirectedUserInstance)
at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity,
SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String
newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString
userConnectionOptions)
at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options,
DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection
owningConnection, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool,
DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32
waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection,
DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject,
TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection,
TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection,
DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions
userOptions)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()
at My_Sql_Program.Program.Main() in c:userspauldocumentsvisual studio 2010ProjectsMy Sql
ProgramMy Sql ProgramProgram.cs:line 30

Answer 1

SqlConnection适用于SqlServer。要连接到MySql，您需要下载一些驱动程序并在项目中引用它，然后改用MySqlConnection。

看看这个问题和这个代码项目示例。

Answer 2

正如@JW Lim和@Kirk Woll所建议的那样，该问题是由使用与SQLServer一起使用的System.Data.SqlClient引起的。

对于这个项目，鉴于我将其保留在本地，因此使用MySql.Data.MySqlClient是解决此问题的正确方法。