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How to Connect SQL server from client to Server PC using Connection string in C#

I am trying to connect SQL Server from Client PC using the below-mentioned string, but it Is showing error as "Login failed for user 'sa'"
Tried string:
public static string connString = #"Data Source=(eg.IP)10.0.255.255,1433; Network Library=DBMSSOCN;Initial Catalog=InventoryProjects;User Id=sa;Password=password";
I have provided IP , userid and passward are correct.
Happening:
DB is not connected from Client PC.
Expectation:
But it should connect as I expected.
Can Anyone Please guiding me to proceed Further, because I am not very much familiar in C# and SQL

Points that spring to mind:
(eg.IP) should be removed from the connection string
Is IP address correct - may not be if it is dynamic?
Is the user id and password correct - use of sa user id may not be allowed?
Check - if you are able to run Microsoft SQL Server Management Studio to connect to the SQL database and check the connection string.

Connecting to a remote SQL Server (SQLExpress) gives "network-related" error, but works using Server Explorer in Visual Studio

I am using NET 6.0 and I cannot make it work.
I am trying to connect using:
var builder = new System.Data.SqlClient.SqlConnectionStringBuilder
{
DataSource = $"{ip}\\SQLEXPRESS, 1433",
InitialCatalog = "xxx",
UserID = "user",
Password = "pass"
};
SqlConnection thisConnection = new SqlConnection();
thisConnection.ConnectionString = builder.ConnectionString;
thisConnection.Open();
However, I keep getting this
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 - No connection could be made because the target machine actively refused it.)
Using exactly the same code on Netframework 4.8 works. Anybody care to explain why? Using the same machine as above, if I use the Server Explorer in Visual Studio then the connection is successful. Also works using Python. I tried ussing the connection string from the Server Explorer connection string and still doesn't work. The connection string from that works using the Server Explorer:
Data Source=xxx.xxx.xx.xx\sqlexpress;Initial Catalog=database;Persist Security Info=True;User ID=sysdba;Password=****
Here is the Server Explored connected:
And the properties:
And then:
SqlConnection conn = new SqlConnection();
conn.ConnectionString = #"Data Source = xxx.xxx.xx.xx\sqlexpress; Initial Catalog = database; Persist Security Info = True; User ID = sysdba; Password = ******";
conn.Open();
But still fails to connect.
I also set the port to 1433 like suggested in Cannot Connect to Server - A network-related or instance-specific error and restarted the service
Also
And still fails to connect using the SqlConnection() (still works using the Server Explorer).
What am I doing wrong?
The SQL Server uses SQL Server Authentication, no Windows Credentials. I connect using IP\sqlexpress.
It doesn't seem to be a network related issue, like I saw in other answered questions, since it is working using the Server Explorer in Visual Studio and also in Python.

I was facing the same issue (Net 5.0). You can use the Connnected Services, which is a collection of tools in Visual Studio that will help you connect to the database. I believe this may be a different approach, but it should work since visual studio will be creating the connection string (same was as per Server Explorer).
https://learn.microsoft.com/en-us/visualstudio/data-tools/add-new-connections?view=vs-2022
https://learn.microsoft.com/en-us/visualstudio/azure/overview-connected-services?view=vs-2022

connection to MySql database on host

I have a problem regarding connecting to my database that is located on my website host server. I have watched few tutorials, took a look on few articles here on stack overflow and read official mysql documentation, and i steel can't connect to it thru my c# console app. This is my code:
string connstring = string.Format("Server=www.vm-consult.com; Database=vmconsul_sitedatabase; Uid=vmconsul_mijovicpetar; Pwd=mypassword");
MySqlConnection connection = new MySqlConnection();
connection.ConnectionString = connstring;
connection.Open();
I have also went to c panel in remote MySQL tab and set "%" to my remote sql hosts.
All the parameters for con string are correct. In server in connection string I also tried to set IP address, did not change anything.
This is exception I get(on the last line: connection.open()):
Unable to connect to any of the specified MySQL hosts.
Any suggestions appreciated. Thanks.

Check connectivity with
telnet www.vm-consult.com 3306

I needed to contact my host provider to enable external connection to the database. Thanks everybody.

How can connect MySql Online Database to C# desktop application

I am creating desktop application in c# but i wont to use Online Database created in mysql.
String mysqlConnectionString = "Server=216.14.120.105;Database=xxx_keys;UID=xxx_root;Password=xxx;Port=3306";
MySqlConnection connection = new MySqlConnection(mysqlConnectionString);
connection.Open();
this is the code i am using but i got an error unable to access host.
where i am wrong and if you have any proper code or details then give me.

If this is a MySQL database in local server user "localhost" for server IP as georgi-it also told. But if this is an external database first try to open a telnet connection on dos-prompt to see if there is some firewall block or something like that:
telnet 216.14.120.105 3306
if you don't get an error message and see a blank page then it means you can reach mysql server

Can't connect to SQL Server 2005 Express from an ASP.NET C# page

I have an MS SQL Server 2005 Express running on a VPS.
I'm using pymssql in Python to connect to my server with the following code:
conn = pymssql.connect(host='host:port', user='me', password='pwd', database='db')
and it works perfectly.
When I try to connect to the server from an ASP.NET C# page with the following code:
SqlConnection myConnection = new SqlConnection("Data Source=host,port;Network Library=DBMSSOCN; Initial Catalog=db;User ID=me;Password=pwd;");
myConnection.Open();
When I run the ASP.NET page I get the following exception at myConnection.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 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)
I tried restarting the SQL Server but I had no luck.
Can anyone point me out to what I'm missing here?
Thanks!

Let's say your host is localhost. When you are using SQLEXPRESS you need to specify that in your Instance Name.
Loke this: Data Source=localhost\SQLEXPRESS if it is bound to localhost. Otherwise it might just work with: Data Source=.\SQLEXPRESS.
If you have management studio installed you can fire that up and check what connection string it is using!

Still doesn't work..
I'm able to connect to the remote server with SQL Management Studio.
I enter host,port\SQLEXPRESS (of course I my actual IP number as the host and my actual port) in the Server Name field, select SQL Security and enter my username and password and it works perfectly.
When I try to connect from the ASP.NET page, it just doesn't work - I get the error aforementioned. Can it have something to do with the company hosting my asp.net page? (GoDaddy)
here is the code again..(assuming my host is 11.22.33.44 and my db is named bla
string connectString = #"Data Source=11.22.33.44,1433\SQLEXPRESS;Network Library=DBMSSOCN;Initial Catalog=bla;User ID=username;Password=pwd;";
SqlConnection myConnection = new SqlConnection(connectString);
myConnection.Open();
Thanks again