I've been looking around for a solution to this issue and the only one that might provide a solution is the only one I haven't tried, because it involves changing system properties. I want to avoid that if I can.
我一直在寻找这个问题的解决方案，唯一可能提供解决方案的是我唯一没有尝试过的方案，因为它涉及到改变系统属性。如果可以的话，我想避免。
The Connection string is correct, but it still won't connect.
连接字符串是正确的，但是它仍然不会连接。
The exception occurs on line 30, which is where the connection string is opened. conn.Open()
异常发生在第30行，这是连接字符串被打开的地方。conn.Open()
Here is the Code:
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();
}
}
}
And when I run it, nothing happens for about 30 seconds, then the SqlException is printed:
当我运行它时，大约30秒内什么都没有发生，然后SqlException被打印出来:
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:\users\paul\documents\visual studio 2010\Projects\My Sql
Program\My Sql Program\Program.cs:line 30
2 个解决方案
#1
5
SqlConnection is for SqlServer. To connect to MySql you need to download some drivers and reference it in your project, and use MySqlConnection instead.
SqlConnection是。状态"置疑"要连接到MySql，需要下载一些驱动程序并在项目中引用它，然后使用MySqlConnection。
Take a look at this question and this CodeProject sample.
看看这个问题和这个CodeProject示例。
#2
0
As @JW Lim and @Kirk Woll suggested, the issue was caused by the use of the System.Data.SqlClient, which is used alongside SQLServer.
正如@JW Lim和@Kirk Woll所建议的，这个问题是由System.Data的使用引起的。SqlClient，它与SQLServer一起使用。
For this project, seeing as I am keeping it local, the use of MySql.Data.MySqlClient is the correct way to approach this.
对于这个项目，可以看到我在本地使用MySql.Data。MySqlClient是解决这个问题的正确方法。
#1
5
SqlConnection is for SqlServer. To connect to MySql you need to download some drivers and reference it in your project, and use MySqlConnection instead.
SqlConnection是。状态"置疑"要连接到MySql，需要下载一些驱动程序并在项目中引用它，然后使用MySqlConnection。
Take a look at this question and this CodeProject sample.
看看这个问题和这个CodeProject示例。
#2
0
As @JW Lim and @Kirk Woll suggested, the issue was caused by the use of the System.Data.SqlClient, which is used alongside SQLServer.
正如@JW Lim和@Kirk Woll所建议的，这个问题是由System.Data的使用引起的。SqlClient，它与SQLServer一起使用。
For this project, seeing as I am keeping it local, the use of MySql.Data.MySqlClient is the correct way to approach this.
对于这个项目，可以看到我在本地使用MySql.Data。MySqlClient是解决这个问题的正确方法。