Develop Reference

Python oracledb continous query notification not sending messages from database

I've been trying to use Continuous Query Notification (CQN) in python script to get notification from database about changes that were made to a specific table.
I have followed tutorial from this link here
https://python-oracledb.readthedocs.io/en/latest/user_guide/cqn.html
Connection to oracle database was successful and I can query the table to get results but I can't get any message from callback function that looks like this
def cqn_callback(message):
print("Notification:")
for query in message.queries:
for tab in query.tables:
print("Table:", tab.name)
print("Operation:", tab.operation)
for row in tab.rows:
if row.operation & oracledb.OPCODE_INSERT:
print("INSERT of rowid:", row.rowid)
if row.operation & oracledb.OPCODE_DELETE:
print("DELETE of rowid:", row.rowid)
subscr = connection.subscribe(callback=cqn_callback,
operations=oracledb.OPCODE_INSERT | oracledb.OPCODE_DELETE,
qos=oracledb.SUBSCR_QOS_QUERY | oracledb.SUBSCR_QOS_ROWIDS)
subscr.registerquery("select * from regions")
input("Hit enter to stop CQN demo\n")
I can see that the registration was created in the database after I run the script but I just don't receive any message about insert or delete after I perform any of those operations through SQL* Plus or SQL Developer.
I am reading other questions and blogs about this functionality but currently without success, so if anyone has any recommendations or has encountered similar problem, please comment or answer here.
Oracle database 12C from docker
Python version is 3.10.7
I am running it in thick mode and for oracle client libraries I am using this command
oracledb.init_oracle_client(lib_dir = ".../instantclient_21_3"
P.S This is my first time posting a question here so if I didn't correctly follow a structure or rules of asking a question please correct me, thanks in advance :)

Please take a look at the requirements for CQN in the documentation. Note in particular the fact that the database needs to connect back to the application. If this cannot be done no notifications will take place even though the registration is successful with the database. With Oracle Database 19.4 a new mode was introduced which eliminates this requirement, but since you are still using 12c that won't work for you. You will need to ensure that the database can connect back to the application -- opening up any ports, ensuring that an IP address is directly specified in the parameters or an IP address can be looked up from the name of the client machine connecting to the database, etc.

How to deploy/store tkinter sqlite database in a server?

I have a login interface, I used tkinter and sqlite3 as database, everything works fine, in my data base stored locally in my PC I've created an username and password which i use to login, I would like to know if there is a way to store only my sqlite.db in a cloud or some server and i can still be able to login with my tkinter interface in any computer using my databese in the cloud.
this is what im using to connect my sqlite database locally and works smootly.
conn = sqlite3.connect('login_file.db')
c = conn.cursor()
user = entry_usuario.get()
contra = entry_contrasena.get()
c.execute('SELECT * FROM superusuario WHERE usuario = ? AND password = ?', (user, contra))
if c.fetchall():
messagebox.showinfo(title='login correcto', message='usuario y contraseña correctos')
else:
messagebox.showerror(tittle=None, message='Contraseña Incorrecta')
c.close()
Psdt: I was trying to use firebase authentication to link with my tkinter login interface, but i wasnt succesful with it (i dont know how to replace it), maybe i should use another server?, any advise please let me know, thanks in advance have a good day

sqlite is a file based database, with no in built network server. So your application needs to access it as a file in a known location.
The only way to do this without a server side function is to host it on a remote network drive - and mount it on your pc; but to do that you leave your data exposed since sqlite data bases aren't password protected in any form - anyone could download the database and open it.
To protect it you would need to implement a network server (maybe on an AWS server - or similar) which gave protected access and exposed the data as a REST API, or even better, don't use sqlite if you want a remote database.

MySQL connection error message after deployment in Pythonanywhere

I deployed my python program in pythonanywhere. This program should be connected to MySQL. I set up the database and I configured my database setting in the config.ini file as below:
[mysql]
host =psedemo.mysql.pythonanywhere-services.com
database =psedemo$psedemo_test
user =psedemo
password =QAZwsx123
When I am running the program from the shell, I am getting the following error in database connection:
"Exception - 1142 (42000): SELECT command denied to user 'psedemo'#'10.0.0.207' for table 'pseapp_osd_products'".
Any idea what is the issue? (I am sure that databases/table are created and my setting also is right)

I am changing my answer as I reviewed Pythonanywhere just now. It looks like you have created a python app there and you are using the MySQL db from them. Your password for Pythonanywhere is different from the MySQL password. When you first generate the database, they ask you to create a password for it and mention that it is different from your Pythonanywhere password. You can create a new password in the database page in case you forgot the password.
Click on your database name in their UI to launch the mysql console. Check the following command.
SHOW GRANTS;
It will most probably show that your user has all the GRANTS.
Now, use the connection details on the page, and the password you created, and try to connect again.
You can also check their help page to connect to MySQL https://help.pythonanywhere.com/pages/UsingMySQL/

try using user = "root" for your user

Another source of this error could be a typo in a join. See some of the discussion here and check that the query you're running is correct.

mssql python Connection

I am using Pycharm and try to link to a mssql server. When I link to a server that requires SQL authentication, the connect is created successfully. However, when I try to link to a server that requires my Windows Authentication, even though I use my username or password of windows log in, I cannot connect successfully. May I know what should be a proper way to setup if it is windows authentication.
I am using the below code:
import pymssql
conn=pymssql.connect(host="10.xx.xx.xx",user="CORPORATE/mywindowsloginname",password="mypassword",database="BIC_reference")
cur=conn.cursor()y
cur.execute('SELECT top 10 * FROM dbo.hi_invoiceline')
print (cur.fetchall())

in order to use Windows Authentication you have to add the property trusted_connection='yes' to your connection string. In this case you can omit user and password:
conn=pymssql.connect(host="10.xx.xx.xx",database="BIC_reference",trusted_connection='yes')

When using Windows Authentication, you should not specify any user credentials. The following should work assuming your Windows account has the relevant permissions:
conn=pymssql.connect(host="10.xx.xx.xx",database="BIC_reference")
I have tested this using pymssql-2.1.3. Using this version there was no need to specify trusted_connection='yes' (see apomene's answer), however, you may want to try that as well in case the above snippet doesn't work.

SQLalchemy - Login with SQL server authentication

I am using SQLalchemy with pyodbc to connect to a SQL server. I can connect using "Windows Authentication":
create_engine('mssql+pyodbc://[ServerName]/[DatabaseName]',echo=True)
That is fine but when I try to login (SQL server authentication) it fails:
create_engine('mssql+pyodbc://[User]:{Password]#[ServerName]/[DatabaseName]',echo=True)
Is my code correct? Am I missing a setting?
Is there a way of listing database users to check the names?

Yes, your connection string is correct. Make sure the user/pwd combinations are correct. Also note that user/pwd can only be used for users which use "SQL Server authentication" (in the code below SQL_LOGIN) and not "Windows authentication"
Given you connect with enough permissions, you can execute the following to see all logins:
for x in session.execute("SELECT name, type, type_desc FROM sys.server_principals"):
print x