Develop Reference

C# code is unable to connect to Azure SQL database

I am trying to connect to a sample database I have created in Azure using C# (.NET Core 3.1)
I have enabled my IP address within Azure's Firewall rules.
I am able to use VS2019's SQL Server Object Explorer to connect and view the database within with no problems.
However, when I run a simple C# app on the same PC to execute a query to count the number of records in a table, it throws the following exception at the point where the connection is opened (conn.Open());
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: TCP Provider, error: 0 - The requested address is not valid in its context.)
The C# code;
using System;
using System.Data.SqlClient;
namespace AzureSql2
{
class Program
{
static void Main(string[] args)
{
string connStr = " Server=tcp:beaconsqlsql.database.windows.net,1433;Initial Catalog=MRP2;Persist Security Info=False;User ID=beaconadmin;Password=********;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;";
Console.WriteLine("Building connection");
try
{
using (var conn = new SqlConnection(connStr))
{
Console.WriteLine("Creating command");
using (var command = conn.CreateCommand())
{
command.CommandText = "SELECT COUNT(*) FROM [dbo].[Table]";
Console.WriteLine("Opening connection");
conn.Open();
Console.WriteLine("Reading database");
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine("Record count: {0}", reader.GetInt32(0));
}
}
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
}
Console.WriteLine("Press Enter to exit");
Console.ReadLine();
}
}
}
I've tried temporarily turning off the firewall on my PC, but that made no difference.
The fact that SQL Server Object Explorer can connect but the C# code cannot makes it sound like there's a problem with the C# code, but I can't see any differences between it and the samples I've looked at.

I created one Azure SQL database and allowed my client IP like below :-
I created one .Net Console application and ran your code, I replaced
using System.Data.SqlClient
with
using Microsoft.Data.SqlClient
You can use any of the above packages.
Copied connection string from Azure Portal > Azure SQL server > Connection string refer below :-
C# Code:-
using System;
using System.Linq.Expressions;
using Microsoft.Data.SqlClient;
namespace AzureSql2
{
class Program
{
static void Main(string[] args)
{
string connStr = "Server=tcp:sqlservername.database.windows.net,1433;Initial Catalog=sqldbname;Persist Security Info=False;User ID=username;Password=password;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;";
Console.WriteLine("Building connection");
try
{
using (var conn = new SqlConnection(connStr))
{
Console.WriteLine("Creating command");
using (var command = conn.CreateCommand())
{
command.CommandText = "SELECT * FROM Products";
Console.WriteLine("Opening connection");
conn.Open();
Console.WriteLine("Reading database");
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine("Record count: {0}", reader.GetInt32(0));
}
}
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
}
Console.WriteLine("Press Enter to exit");
Console.ReadLine();
}
}
}
Output :-
I tried to run the code with the connection string format you mentioned in the comments :-
Data Source=azuresqlservername.database.windows.net;Initial Catalog=databasename;User ID=siliconuser;Password=password;Connect Timeout=30;Encrypt=True;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False
And I was able to run the same code above and got the desired output:-
When I tried to change the Azure SQL server name in the connection string, I got the same error code as yours, refer below :-
Verify if your connection string has any syntax missing and validate it from Azure Portal.

I ended up taking a copy of the project home and running it on my home PC, and it worked correctly and reliably (after telling Azure to allow that IP address as well)
It turned out the answer was embarrassingly obvious - in addition to the standard Windows 10 firewall, my work PC is running another virus protection/firewall software, and that also needed to be told to allow the app thru.
Definitely one to remember for next time... Although I am kind of intrigued that on two occasions (once mentioned above, once afterwards) out of a few hundred attempts the app did manage to get thru and connect.
Thank you everyone for your answers and help.

Connecting Visual Studio to a SSH Tunneled MySQL Server

I was looking for a workaround for configuring my database connection.
I saw that opening 3306 port is dangerous and we should be using SSH Tunnel instead to connect to the database.
I configured my MySQL server using docker and successfully connected it using MySQL Workbench
Now I have to configure and connect it to Visual Studio 2022 to be able to query to the database.
Visual Studio 2022 is only supported by MySQL Data thru NuGet packages which doesn't have a gui connection setup.
I installed Visual Studio 2019 which is officially supported by MySQL Database and can be configured thru Data Source.
How can I setup MySQL Database connection to my Visual Studio if it's SSH Tunnel configured.
Add Connection window only shows basic information about the connection. I'm not sure how to configure this over a SSH Tunnel.
Thank you in advance.

For security reasons, sometimes the database server can only be accessed through SSH. For example, the MySql service is installed on server A, and machine A can only be accessed by machine B, and the deployment environment may be on machine C. In this case, C The server connects to the A server through the B server. At this time, SSH connection is required, and the SSH.NET class library is required:
code show as below:
using MySql.Data.MySqlClient;
using Renci.SshNet;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace SSHMySql
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
SSHConnectMySql();
}
public void SSHConnectMySql()
{
string SSHHost = "*.*.*.*"; // SSH address
int SSHPort = ; // SSH port
string SSHUser = "user"; // SSH username
string SSHPassword = "pwd"; // SSH password
string sqlIPA = "127.0.0.1";// Map addresses In fact, it is possible to write other MySql on Linux My.cnf bind-address can be set to 0.0.0.0 or not
string sqlHost = "192.168.1.20"; // The IP address of the machine installed by mysql can also be an intranet IP, for example: 192.168.1.20
uint sqlport = ; // Database port and mapping port
string sqlConn = "Database=mysql;Data Source=" + sqlIPA + ";Port=" + sqlport + ";User Id=user;Password=pwd;CharSet=utf8";
string sqlSELECT = "select * from user";
PasswordConnectionInfo connectionInfo = new PasswordConnectionInfo(SSHHost, SSHPort, SSHUser, SSHPassword);
connectionInfo.Timeout = TimeSpan.FromSeconds();
using (var client = new SshClient(connectionInfo))
{
try
{
client.Connect();
if (!client.IsConnected)
{
MessageBox.Show("SSH connect failed");
}
var portFwdL = new ForwardedPortLocal(sqlIPA, sqlport, sqlHost, sqlport); // map to local port
client.AddForwardedPort(portFwdL);
portFwdL.Start();
if (!client.IsConnected)
{
MessageBox.Show("port forwarding failed");
}
MySqlConnection conn = new MySqlConnection(sqlConn);
MySqlDataAdapter myDataAdapter = new MySqlDataAdapter();
myDataAdapter.SelectCommand = new MySqlCommand(sqlSELECT, conn);
try
{
conn.Open();
DataSet ds = new DataSet();
myDataAdapter.Fill(ds);
dataGridView1.DataSource = ds.Tables[];
}
catch (Exception ee)
{
MessageBox.Show(ee.Message);
}
finally
{
conn.Close();
}
client.Disconnect();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
}
}
Note: If an error occurs, you can stop the MySql service on the local (development machine).
Required dll: SSHDLL.rar

You can fill in the following information to configure the connection to the MySql database.
Server name: Enter the IP address of MySQL, which is 127.0.0.1 as seen in your SSL connection information.
User name: Enter the user name of Mysql
Password: Enter the password of Mysql
Database name: Enter a test database
Hope it can help you

SQL Server 2014 Connection and Select in Unity3D

Friends need your help!
I'm doing game project as my qualification work in University. I do this in Unity3D.
As main part of my project I must use databases in my qualification work.
I have created database in SQL Server 2014 Express and trying to use this database in my Unity project. My code is below.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Data.SqlClient;
public class GObj : MonoBehaviour {
public void WorkWithDatabase()
{
string connectionstring = #"Data Source=127.0.0.1;Initial Catalog=GameForDiplom;Integrated Security=True;";
SqlConnection Myconnection = new SqlConnection(connectionstring);
Myconnection.Open();
Debug.Log("OPEN SUCCESS!");
using (var cmd = Myconnection.CreateCommand())
{
cmd.CommandText = #"SELECT * FROM [User]";
using (var rdr = cmd.ExecuteReader())
{
while (rdr.Read())
{
Debug.Log(rdr["IDuser"] + "\t" + rdr["Nickname"] + "\n");
}
}
}
Myconnection.Close();
Debug.Log("CLOSE SUCCESS!");
}
}
During connection to my database in game i receive this
ERROR:
SocketException: The connection is not established, since target machine actively refused the connection request.
Please, I would like to see working code in C# and your settings of SQL 2014 Express which you use. I tried to open TSP port 1433 but I receive this
ERROR:
NullReferenceException: Object reference not set to an instance of an object
Mono.Data.Tds.Protocol.TdsConnectionPool.GetConnection ()
Friends, i'm not pro programmers as you can see, but i'm trying to be better! Please, help!
Thank you for help, Friends!

Oracle: How to allow leading/trailing spaces in ODP.Net connection string values?

My C# app connects to Oracle using following connection string format:
Data Source=tnsEntry;User Id=myUsername;Password=myPassword;
Now if there's a user id that starts with space like ' abc' (excluding quotes), how can I specify it in the connection string? Putting it in single/double quotes results in error Ora-1017: Invalid username/password.
Using Oracle.DataAccess, Version=2.112.3.0. Connecting to Oracle 11g.
Reproducible at my end in this minimal sample:
using System;
using Oracle.DataAccess.Client;
namespace ConsoleApplication5
{
class Program
{
static void Main(string[] args)
{
var con = new OracleConnection("User Id=\" abc\";Password=system05;Data Source=REFUPG141");
try
{
con.Open();
Console.WriteLine("connected.");
}
catch (Exception e)
{
Console.WriteLine(e);
}
}
}
}

Surrounding the username with double-quotes worked for me:
Note that you need to use double-quotes when creating your user:
SQL> create user " DUMMY" identified by "pass";
User created.
SQL> grant connect, create session to " DUMMY";
Grant succeeded.
SQL> conn " DUMMY"/"pass";
Connected.
Then in .NET I've used this connection string and worked fine:
Data Source=localhost/mySid;User Id=" DUMMY";Password=pass
[EDIT] Important information:
I'm using the Managed .NET Oracle Provider

.NET and sql server database link

I'm a real noob in .NET and i'm trying to link a simple command line application (in C#) with a SQL server database. I'm now able to connect the program with the database but not to recover the data that are in it. Here is my code :
using System;
using System.Data;
using System.Data.SqlClient;
namespace ConsoleApplication1
{
class Program
{
static void Main()
{
string connectionString = GetConnectionString();
string queryString = "SELECT USER_ID FROM dbo.ISALLOCATEDTO;";
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand command = connection.CreateCommand();
command.CommandText = queryString;
try
{
connection.Open();
SqlDataReader reader = command.ExecuteReader();
int i = 0;
while (reader.Read())
{
i++;
Console.WriteLine("Field "+i);
Console.WriteLine("\t{0}",reader[0]);
}
reader.Close();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
//Console.WriteLine("Hello world");
string x = Console.ReadLine();
}
static private string GetConnectionString()
{
return "Data Source=FR401388\\SQLEXPRESS;Initial Catalog=Test;";
+ "Integrated Security=SSPI";
}
}
}
But when i'm running it and even if my table is not empty (I've seen it in the sql server studio), I cannot recover the data by using the read() method.
What I've done so far : try to change the name of the datatable with a fake one : the datatable is not found (so the link between sql server database and programm seems to be valid).
I'm using Windows Authentication in sql server, dunno if it's changing anything... (Once again : i'm very new to all of that).
Thanks !

Your code should work.
A possible cause is: You are looking at a different database.
This is quite common if you use Server Explorer inside VS with a connectionstring different from the one used in code.