Develop Reference

What Is the Syntax for Including the Service Name in a Connection String?

I have a C# ASP.Net MVC web application. I am trying to successfully connect to an Oracle database.
I am getting a "ORA-12514: TNS:listener does not currently know of service requested in connect descriptor" error.
I do not have access to the server the database is on. But I do have access to Oracle SQL Developer, which I have installed on my machine.
In my C# code I am setting the connection string like this:
ConnectionString = "DataSource=XXX.XX.XXX.XXX/abcd,1521;User ID=userid;Password=password;";
abcd should be the service name. and 1521 is the port number.
I understand that my connection string might not be the cause of the error, but I want to rule it out. Also, I know the more proper way of doing things is probably to set the connection string in web.config and retrieve it as needed, but I am doing it this way just for ease of testing until I know I am able to connect to the database successfully.
What is weird to me, is that I was able to connect to the database using Oracle SQL Developer using the same IP address, port number, service name, username, and password I am using in my connection string.
Primarily, I would like help knowing if my connection string looks valid. If you have additional thoughts about what the issue could be, that would also be appreciated.
using this command in Oracle SQL Developer:
select sys_context('userenv','service_name') from dual;
I am able to determine that the service name I am using in my connection string is one that exists, although I guess this does not guarantee that the service is up.
I am not a DBA by any means. In fact, I am still new to .Net and web development in general, but I have been assigned to troubleshoot this issue. Any help is appreciated.

I don't recall seeing the following format
DataSource=XXX.XX.XXX.XXX/abcd,1521
as valid (which doesn't mean its not, I've just not seen it).
The more common ones I've seen are:
DataSource=XXX
where XXX is a reference to your tnsnames.ora file
DataSource=//nnn.nnn.nnn.nnn/service_name
DataSource=//nnn.nnn.nnn.nnn:port/service_name
So maybe try those variants and see how you go. There's also more definitive list of alternatives at https://www.c-sharpcorner.com/UploadFile/nipuntomar/connection-strings-for-oracle/

I ended up figuring this out. My connection string format I don't t think was correct. I changed it to be:
ConnectionString = "DataSource=XXX.XX.XXX.XXX/abcd;User ID=userid;Password=password;";
Basically, I just took off the port number. In my case, the default port was what I needed anyway. Not sure what I would have done had I needed to specify the port number.

As new to Oracle I struggled a few days finding solution to this
this article helped me alot
As of Oracle 21 c
This is my Connection string for C#
Password=dev;Persist Security Info=True;User ID=Dev;Data Source=localhost:1521/XEPDB1
Keep in mind Dev is Username which is also the Schema name for Oracle

How to avoid connections against empty/null database by Entity Framework

We use entity framework to read from an existing database.
This is a simplified version of our code.
using (my context context = new mycontext())
{
if(context.Database.Connection.State == System.Data.ConnectionState.Closed)
{
_logger.Info(" Opening the connection to the database");
context.Database.Connection.Open();
}
context.Configuration.LazyLoadingEnabled = false;
IQueryable<mymodel> people;
people = context.People.OrderBy(x => x.Firstname);
_lstContacts = people.ToList();
if (context.Database.Connection.State != System.Data.ConnectionState.Closed)
{
context.Database.Connection.Close();
context.Database.Connection.Dispose();
_logger.Info(" Connection to the database Closed");
}
}
It works 100% of the time, but...
On our UAT environment we can see failed connections to the Microsoft SQL server with the error:
Login failed for user "my user". Reason: Failed to open the explicitly
specified database "null". Client my IP.
For us, these are ghost connections because at the time when we see the errors in the SQL server, our code is not executed.
Initially we didn't close and open the connection explicitly, we just added it trying to control when EF open and closes the connection, but it didn't fix the issue.
Our connection string is using the following format:
<add name="MYCN" connectionString="metadata=res://*/CVs.Cvs.csdl|res://*/CVs.Cvs.ssdl|res://*/CVs.Cvs.msl;provider=System.Data.SqlClient;provider connection string="data source=myserver\;initial catalog=mydatabase;Integrated Security=;User ID=myuser;Password=XXXXXXX;MultipleActiveResultSets=True;App=EntityFramework"/>
As you can see, we are specifying the database in the connection string and our user only have access to our database, so we understand the error when EF doesn't include the database in the connection string, but we don't understand why it's trying to perform these connections.
We know the connections are coming from our application, because we are the only one using that specific user, the IP is the IP of our server, and because the logs in SQL server tell us that the application is "EntityFramewrok"

I didn't personally see the error before, but researched for you and seen that many people suffered from the same problem discussed here: https://blogs.msdn.microsoft.com/sql_protocols/2006/02/21/understanding-login-failed-error-18456-error-messages-in-sql-server-2005/
I read all the messages in the website specified, and here are the solutions offered and at least one other user confirmed that it worked. You might not use 2005 as you didn't specify your version in your question, some solutions I believe will still work for you. Try the list below.
Solution list:
1) Please check the state number of this error and search solution by the state number in addition to the message, might give your more accurate solution proposals. Most common states are listed:
All state-error descriptions you can find here: https://sqlblog.org/2011/01/14/troubleshooting-error-18456
2) Make sure the username and password are correct.
3)
Logon to SQL Server using windows authentication.
Right click in the query window that appears and select "Open Server in Object Explorer"
Go to object explorer and open the "Security" folder and then the "Logins" folder.
Double-click the "sa" user and change the password. Also, like another user mentioned above, untick the "Enforce Password Policy" in
addition to resetting the password.
4) Try to change the password and turn off the policy, and try with new password.
exec sp_password #new = ‘sqlpassword’, #loginame = ‘sa’
alter login sa
with password = ‘sqlpassword’ unlock,
check_policy = off,
check_expiration = off
5) Run your application/browser and SSMS (if you work on it) in administration mode.
6)
Open Windows Services
Configure Microsoft Single Sign-on Service to use the proper account
Open Central Administration >> Operations >> Manage settings for single sign-on
Configure properties to use the same account used for Microsoft ‘Single Sign-on Service
7) Go to Sql server configuration manager and Enable TCP/IP and named pipes
8)
go to sql server
right click on server, choose properties
click on security
on server authentication, enable SQL Server authentication
These might help:
https://www.wikitechy.com/errors-and-fixes/sql/login-failed-error-18456-severity-14-state-38-reason-failed-to-open-the-explicitly-specified-database
https://dba.stackexchange.com/questions/90445/login-failed-for-user-error-18456-severity-14-state-38

I think this is just an access issue for myuser in the UAT environment. Just make sure myuser has access in the UAT environment for UAT database and you should be good.

Can't access database, access denied for user

I got this error message while connecting my app with the database at my website.
If i try using XAMPP using my computer, its work well.
FYI, the username and password is same as username and password that i created using XAMPP.
and also grant the privileges.
this is the connection string. for example the server is 174.125.80.140, the database name is myDB, the Uid is alfred, and the password is Alfred111.
MySqlConnection conn = new MySqlConnection("Server=174.125.80.140; Database=myDB;Uid=alfred;Pwd=Alfred111;");
I'm using MySQL client version: 4.1.22.
I'm still can't access the database. is there any solution??

If you are using MySQL workbench,
1) Start the workbench
2) click on the option "Users and Privileges" under SECURITY
3) click on add user (for the specific user), this is more secure because it lets you handle who has access over your database and lets you control access.
however if you want to grant access a large number of users for an application like c# application, then hard-code the username and password in the application, from the user privileges that you have set above.
Hope this helps (^_^)

Yes, you may have supplied the user and password correctly but have you configure the server (new server) to accept Uid=alfred;Pwd=Alfred111;?
Adding User in MySQL Server

If your app is on a different host that the MySQL server then you most likely need to add a new user granting permission for that host. Your alfred user is probably allowed by localhost and nothing else. Try CREATE USER 'altred#'%' identified by 'password'; and then grant that user privileges on myDB.
You can replace % with a specific IP address or hostname as well, % allows the connection from any host which is not necessarily safe.
You can try the following query to see the allowed user/host combos:
SELECT `User`, `Host` FROM `mysql.user`
Hope that helps.

User does not exist in MySQL , c# and asp.NET MVC

I am working on development machine without making any user account [i have three of four account who comes when i installed them].
so i open the connection everywhere by a globals variable who hold the connectionstring off-course value of variable can not be changed it's constant.
i open the connection using root account who come by default in mysql server. they work fine everywhere.
but my code try to run a command then server return the error that
The user specified as a definer ('admin'#'localhost') does not exist
i don't know why i got this error even in debug i found that connection open by root and they work fine everywhere else.
so the problem is why they tell me about admin#localhost even the connection my code open by root.
are their anything my code try to do who need authentication or need admin account even they not have then give me exception.
Are you know that what is gone wrong.

I got this error after DB was moved to another server.
There no such user 'admin' so I got the error.
Solution:
log into mysql as root
grant all on *.* to admin#localhost identified by "s!5_superp#ss!";
flush privileges;

Error connecting to Oracle from Visual Studio

I am not able to connect to Oracle using connection string and the correct password. I've tried the same parameters in SQL developer and sqlplus(commandline) and they are working. I even tried changing the password but no use.
Any ideas what might be wrong or where should I start looking?
The exact Oracle error is :
invalid username/password password, logon denied
and after trying a few times account is getting locked with
the account is locked

When I've run into this, it has ALWAYS been an issue with my connect string.
What is your connect string? It should be something like "User Id=[ID]; Password=[PWD]; Data Source=[DB]"
Of course, you'd replace [ID], [PWD] and [DB] as appropriate.

Is it just your computer that exhibits the problem, or are others seeing it as well?
Can you test your connection in the ODBC Data Source Administrator? Does that work?

Try to install the Oracle Developer Tools for Visual Studio. It's free but you need to register, also free.

You need to unlock the account.
(From above referenced site)
SQL> ALTER USER username ACCOUNT LOCK;
SQL> ALTER USER username ACCOUNT UNLOCK;

Actually the problem was with cache on the computer. Even though I am giving "server='correctdb'" visual studio was taking "server='olddb'" as input and hence I am not able to connect. Pathetic but that's what happened.