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Can't connect to remote MySQL (MariaDB) database in .NET but I can with Java

I am trying to migrate some code from JavaFX to use C# for Windows Forms. In Java, I was using JDBC and could connect just fine programmatically. Nos that I am trying to use C# I am getting this error:
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).
I am using the same server address and credentials. I'm using System.Data.SqlClient. I've tried a bunch of different combinations but can't get the connection string to work.
String connectionString = "server=[Server URL];database=[Database Name];persist security info=true;user id=[Username];pwd=[Password]";

Here is an example of the mysql connection string:
string connectionString = "datasource= <database ip or domain>; port=<port, usually 3306>;username=<database user>;password=<user's password>;SslMode=none<this is important if you don't use ssl>;database=<your database>";
I think the reason you can't connect is because you haven't specified the SslMode.

How to Grant a Java Web App Access to a Digital Ocean Droplet

I'm hosting mysql server on a Digital Ocean droplet, and I am trying to figure out how to grant a Spring Boot web application access to the droplet, so that it can connect to the database. I configured the droplet so that it can only be reached via an ssh tunnel (i.e.: I disabled password authentication), but the database server itself can be connected with a username and password.
I know how to connect to the database using Connector/J, configuring datasources, and so forth. However, the extra security layer of Digital Ocean is new to me, and I'm not sure how to approach this problem.
EDIT: When I run the application and try to hit an endpoint, I get the following error:
The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: null, message from server: "Host '<my network hostname>' is not allowed to connect to this MySQL server"] with root cause

So, I was mistaken in thinking that the authentication issue was with the Digital Ocean droplet. As the error message (see question above) indicates, the Spring Boot application was able to get to the remote mysql server, and the authentication issue occurred there. It turns out that the mysql user I was attempting to connect with could only be used on localhost.
So, I created a new mysql user and tied it to my local machine's public IP address, and that solved the issue. For details on how to accomplish this, please read the following answer:
Host 'xxx.xx.xxx.xxx' is not allowed to connect to this MySQL server

Can't connect to Sql Server database using JDBC

I'm trying to make a connection to an already existing database in SQL Server 2012n with Netbeans 8.
Using the connection wizard I select Sql Server 2012 and enter the credentials and fields.
However I get the message that a connection cannot be established.
You can see screenshots of the entered fields:
I also tried using "localhost" instead of "STIJN" this didn't work. I also tried with the default port "1433". Also didn't worked, however what port should this be? Where can I see what port I'm using? Maybe the error lies in the port, otherwise I wouldn't know where I made a mistake.

Go to your SQL Server configuration manager -> SQL server network configuration -> protocols for SQLEXPRESS -> TCP/IP (double click on it for properties).
On protocol page set enabled to Yes.
On IP Addresses page, scroll to bottom.
TCP Dynamic Ports: 54629
TCP Port: 1433
Apply and ok.
Make a connection with:
Host: localhost
Port: 1433
Your credentials
Instance field = blank.
This should work.

The TCP/IP connection to the host localhost, port 1433 has failed

I'm getting this 2 errors repeatedly when I'm trying to connect eclipse with sql server through jdbc. Could anyone help me with this or explain why am I getting this?
1. The TCP/IP connection to the host localhost, port 1433 has failed.
2. The driver could not establish a secure connection to SQL Server by using Secure Sockets Layer (SSL) encryption.
Thank you.
String driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
Class.forName(driver).newInstance();
String connString ="jdbc:sqlserver://localhost:1433/databaseName=Engg_Street;instance=SQLSERVER;encrypt=true; trustServerCertificate=true";
String username = "Vijayalakshmi";
String password = "";
conn = DriverManager.getConnection(connString,username,password);

You need to Go to Start > Microsoft SQL Server > Configuration Tools > SQL Server Configuration Manager
When it opens Go to
SQL Server Configuration Manager > SQL Server Network Configuration > Protocols for SQLExpress
Where you'll find the Protocol TCP/IP, if disabled then Enable it Click on TCP/IP, You'll find its properties.
In this properties Remove All the TCP Dynamic Ports and Add value of 1433 to all TCP Port
and restart your SQL Server Services > SQL Server
And Its Done...

If you are running SQLSERVER EXPRESS:
Use "SQL Server Configuration Manager" or write "mmc.exe" on Win+R and search "SQL Server Network Configuration", in the "Protocols for SQLEXPRESS" enable the option TCP/IP
I hope than this works for somebody!!

For this kind of issue - you can resolve by checking whether all sql server related services are running or not.
TO check Start -> Run -> services.msc
check services related to sql as
SQL Server (MSSQLSERVER)
SQL Server Agent (MSSQLSERVER)
SQL Server Analysis Services (MSSQLSERVER)
SQL Server Browser
SQL Server Integration Services 10.0
SQL Server Reporting Services (MSSQLSERVER)
SQL Server VSS Writer
Start all the above services. and set to start up type to Automatic.
SQL Active Directory Helper Service is not required to keep running.
It can used to deal with error SQL server connection error 2
and
with
he TCP/IP connection to the host localhost, port 1433 has failed. Error: "Connection refused:

It can used to deal with error SQL server connection error 2 and with he TCP/IP connection to the host localhost, port 1433 has failed. Error: "Connection refused: https://www.youtube.com/watch?v=R8_jjkeulEw
or please check if the table name is duplicated, i changed the table name --> problem solved

java.sql.SQLException: Single-Sign-On is only supported on Windows. Please specify a user name

I am using the jTDS driver in order to connect to an SQL Server database from my Android application, which uses the Windows Authentication. As advised in the FAQs, I read the READMESSO file and as told, I placed the native SPPI library (ntlmauth.dll) in the system path (defined by the PATH system variable)
However, when I try to connect to the database using the following code:
String driver = "net.sourceforge.jtds.jdbc.Driver";
Class.forName(driver).newInstance();
String connString = "jdbc:jtds:sqlserver://192.168.56.1/MyMovies;";
Conncection conn = DriverManager.getConnection(connString);
I get the following exception:
java.sql.SQLException: Single-Sign-On is only supported on Windows. Please specify a user name.

Since you are connecting from an android device, you would not be able to get the SSO credentials required by the driver to connect to SQL server. The setting you referred to works only if the java program trying to connect to the DB is on a windows machine, which is clearly mentioned by the error message.
Unless your application has authorization based on the SSO user connecting to the DB, you should have an SQL Server user-based authentication mechanism to connect to the server and all authorization procedures should be tied to this user.

You might have to give the username also.
"jdbc:jtds:sqlserver://192.168.56.1/MyMovies;instance=SQLEXPRESS;user=foo"