I have an AWS EC2 instance running. I've tried to make a connection to my MySQL like this in C#
MySqlConnection l_DBConn = new MySqlConnection();
l_DBConn.ConnectionString = "Server=my-ec2.compute-1.amazonaws.com;Port=3306;Database=mydatabase;uid=root;password=mypassword;port=3306;charset=utf8"
MySqlCommand command = l_DBConn.CreateCommand();
command.CommandText = "select * from users";
MySqlDataReader Reader = command.ExecuteReader();
The error received when I run the last line is "Connection must be valid and open.". I still can connect to my instance using Filezilla,Putty and MySQL WorkBench also(with SSH). And I'm using MySql.Data.MySqlClient in my code. Anyone has any idea about this? Is this because my instance does not allow remote access or a problem with my connection string?
Thank you in advance,
Wayne.
Edit: The problem is solved by adding l_DBConn.Open() and add my IP to the server using RANT ALL PRIVILEGES ON . TO root#'hostname' IDENTIFIED BY 'root-password'. Thanks!
Try calling l_DBConn.open() before executing the reader. The error implies that the connection is not open since you haven't explicitely opened it
Some ideas:
Make sure you can connect to your database locally first.
Is Sql Server setup to allow mixed authentication
Have you open port 3306 in the EC2 firewall and the windows firewall if you're running it.
Related
I have a pretty strange problem when trying to connect my C# program to an existing Firebird server.
First of all, this is reproducable with the default connection example from the Firebird documentation at https://github.com/FirebirdSQL/NETProvider/blob/master/Provider/docs/ado-net.md
using (var connection = new FBConnection("database=192.168.0.150:c:\\Data\\demo.fdb;user=sysdba;password=m#sterkey"))
{
connection.Open();
using (var transaction = connection.BeginTransaction())
{
using (var command = new FbCommand("select * from demo", connection, transaction))
{
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
var values = new object[reader.FieldCount];
reader.GetValues(values);
Console.WriteLine(string.Join("|", values));
}
}
}
}
}
It all works fine when I am on my machine, I also can connect to a Firebird server on my coworkers PC.
But I cannot connect to the Firebird server on my other development server. I found an answer in another question and want to tell you that the server does not have internet access.
https://stackoverflow.com/a/57569057/2785084
This is the exception I get:
FirebirdSql.Data.FirebirdClient.FbException: "Unable to complete
network request to host " No message for error code 335544721 found."
IscException: Unable to complete network request to host " No message
for error code 335544721 found. IOException: Unable to read data from
the transport connection: An existing connection was forcibly closed
by the remote host
I already updated to the latest stable Version of Firebird. I can guarantee that the server is running and no firewall is blocking my connection, because when I try to connect with our old Delphi program, everything works. I also can connect using the lightweight Firebird management tool Flamerobin from Flamerobin.org, which is written in C++, I think.
When I try to connect with DBeaver I get the following message:
[SQLState:28000, ISC error code:335544472] Your user name and
password are not defined. Ask your database administrator to set up a
Firebird login.
I'm pretty sure that the user and password are correct. I do not use the default password, but a password with an # sign in it, maybe it has something to do with that.
I now have 2 programs that can Connect (Delphi and C++), and two that cannot connect (C# and Java). Does anyone have any clue or tweak how to change the connection that I can connect to the server?
Thanks to Mark Rotteveel for the comment which got me to the solution.
I can connect with the default password "masterkey", so it is obvious that the srp user was created with the default credentials and therefore a connection with the other credentials is not possible.
I have to correct the users in my old server.
Thanks for the hint that ADO.NET only supports srp.
I'm trying to connect a UWP app written in C# to a MySQL DB hosted on another machine on the local network (it's on a Raspberry Pi, but I doubt that makes a difference). The code I have right now is:
string M_str_sqlcon = "Server=192.168.0.101;Port=3306;Database=****;User ID=****;Password=****;";
MySqlConnection mysqlcon = new MySqlConnection(M_str_sqlcon);
MySqlCommand mysqlcom = new MySqlCommand("select * from mysql.users", mysqlcon);
mysqlcon.Open();
However, the code fails with a 'Unable to connect to any of the specified MySQL hosts.' error. Here's the pic of the error pop-up.
I've tried changing the server address, and if I enter one that isn't present on the local network, it fails with a different error (along the lines of Unable to connect to any of the specified MySQL hosts, cannot reach target server).
I've tried various connection strings I've found around StackOverflow, and in MS' own docs, but nothing seems to help.
I can properly ping the DB IP from the machine I'm developing this app on, and I can access the database normally using MySQL Workbench, so I'm sure it isn't a problem with the user permissions/settings.
Any help would be appreciated!
Try to connect with the database using some GUI tools. If it works you will be sure that there is a problem with your application. It could be network problems etc.
I've built a C#-application and now I want to connect that application with an MySQL-Server that is running in my local network.
For this purpose I used the MySQL-connector like the following:
string connectionString = "server=192.168.0.11;uid=User1;pwd=PWD1234;database=Caller;";
MySqlConnection conn = new MySqlConnection(connectionString);
conn.Open();
But everytime I want to connect to the database and open the connection, it fails with the error "Unable to connect to any of the specified MySQL hosts.".
I've tried a couple of different things:
Granted all privileges on the user
GRANT ALL PRIVILEGES ON . TO 'User1'#'%' IDENTIFIED BY 'PWD1234' WITH GRANT OPTION; FLUSH PRIVILEGES;
Changed the MySQL-configuration file
Now it doesn't contain a line like bind-adress or skip-networking anymore.
Restarted the MySQL server
So where is the problem? I am not able to figure it out...
The server is running on Ubuntu Server, actual version.
Thank you and with best regards,
Nicolas
I have a windows form application in C# and sometimes I want to push some data table from this application to an online mySql server which is hosting all data for my website in PHP. To do that I've installed :
1- MySql for visual studio version 1.2.3
2- MySql Connector.Net 6.9
Also, I have enabled Remote MySql on the server so I can make the connection. I used the '%' wildcard for the meantime because my IP address is dynamic.
my basic c# connection code is as below :
MySql.Data.MySqlClient.MySqlConnection conn;
string myConnectionString;
myConnectionString = "Server=*******;Database=*******;Uid=******;Pwd=********;";
try
{
conn = new MySql.Data.MySqlClient.MySqlConnection();
conn.ConnectionString = myConnectionString;
conn.Open();
MessageBox.Show("connected successfully..");
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
MessageBox.Show(ex.Message);
}
Unfortunately, every time I run this code I am getting an error which says
"Unable to connect to any of the specified MySQL hosts".
I don't' know where the problem is. Is it something on the UNIX server which
blocks the connections or some other thing which I need to do. I am also new to the CPanel interface and how to deal with it.
I appreciate all the help provided.
Many Thanks.
http://www.codeproject.com/Articles/43438/Connect-C-to-MySQL
Did you see that? You can try it.
I know this is an old question but I had the same issue many years ago and the only way I could get it to work was to enable remote MySql on the server I was running. This basically means allowing remote connections to access the DB. This of course is very risky and poses a major security problem. You can limit connections from specific IPs, but in my opinion its best to have a local DB and then perhaps push updates to an online source somehow.
I use the following function for insert the value in database through the stored procedure.but i have the exception in sqlConnection.Open();How to solve this?
try
{
string dbConnectionString = "something";
SqlConnection sqlConnection = new SqlConnection(dbConnectionString);
SqlCommand command = new SqlCommand("sp_Test", sqlConnection);
command.CommandType = CommandType.StoredProcedure;
command.Parameters.AddWithValue("#id ", SqlDbType.Int).Value = TextBox1.Text;
command.Parameters.AddWithValue("#FullName", SqlDbType.VarChar).Value = TextBox2.Text;
sqlConnection.Open();
command.ExecuteNonQuery();
sqlConnection.Close();
}
catch (SqlException ex)
{
Console.WriteLine("SQL Error" + ex.Message.ToString());
}
Well, the error you are getting doesn't really have anything to do with stored procedures, but I can answer the question of "how to solve this?" in the context of the exception you are getting.
First, I hope you are not using "something" as the actual connection string to your sql server. You should be using a real connection string. Here are some various examples you can use to connect to SQLServer - http://www.connectionstrings.com/sql-server-2005
Using the first example from the above url
Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;
You'll want to change "myServerAddress" to the ip address or host name of the server. This could be "localhost" or it could be another computer you have on the network. Change "myDataBase" to the name of the database you created, and make sure the name matches exactly as the database might be configured with case sensitivity. And finally change "myUsername" and "myPassword" to the user and password of the account you use to access the server under Sql Server Management Studio.
Now, assuming you have actually done the above, here are some steps you can take to debug connection issues.
Ping the computer - from and command prompt type "ping servername" where servername is the name or ip address of the server that runs SQL Server. If you don't get a response from the server then you need to debug your local network.
If the server is running locally try using "." for the "myServerAddress" value. If it's sqlserver express edition, use the express format - ".\SQLExpress" or "myServerAddress\SQLExpress"
If SQL Server is running on another computer try each of the three links under the section "More Information" from this kb article - http://support.microsoft.com/kb/914277 That will ensure remote connections are supported.
But the real issue is that you cannot connect to the database. I recommend searching for solutions to that problem first. Or perhaps supply more information about your setup here on SO in a different question.
Hope that helps,
-Marcus