Develop Reference

Stored Procedures Python

I need to create a linked server in MS SQL Server for 2 AWS RDS servers,
from Python 2.7. For this I use the pymssql library. The SQL commands are executed with a SQL Client without problems, the linked servers are created, they can be consulted that exist and can be used.
The problem occurs when you execute a SQL creation in Python (from an instance AWS Linux, in the same AZ), then you get the following error message.
Simple SQL queries from python (such as a Select) work without problems using pymssql.
The same happens when a stored procedure is created in the database and it called from python, if the instructions to create the linked servers are included then the same error is received. If you create the procedure in the sql in python the result is similar.
Does anyone know how to do it? Thank you very much for the help.
Linkedserver Commands:
EXEC master.dbo.sp_addlinkedserver #server = N'linkserver1', #srvproduct=N'', #provider=N'SQLNCLI', #datasrc=N'aa.bb.cc.dd';
EXEC master.dbo.sp_dropserver #server = N'linkserver1';
EXEC sys.sp_linkedservers;
Python Code:
**import pymssql
def main():
conn = pymssql.connect(server, user, clave, base)
cursor = conn.cursor()
cursor.execute("EXEC master.dbo.sp_addlinkedserver #server = N'RDSPrivate01', #srvproduct=N'', #provider=N'SQLNCLI', #datasrc=N'win-01.nnnnnn.us-west-1.rds.amazonaws.com'")
if __name__== "__main__":
main()**
Message Error:
cursor.execute("EXEC master.dbo.sp_addlinkedserver #server =
N'RDSPrivate01', #srvproduct=N'', #provider=N'SQLNCLI',
#datasrc=N'win-01.nnnnnnnnnnn.us-west-1.rds.amazonaws.com'") File
"src/pymssql.pyx", line 468, in pymssql.Cursor.execute
pymssql.OperationalError: (15002, "The procedure
'sys.sp_addlinkedserver' cannot be executed within a transaction.
DB-Lib error message 20018, severity 16:\nGeneral SQL Server error:
Check messages from the SQL Server\n")
Links used:
https://aws.amazon.com/blogs/database/implement-linked-servers-with-amazon-rds-for-microsoft-sql-server/
http://www.pymssql.org/en/stable/pymssql_examples.html#important-note-about-cursors

Connecting to local SQL Server instance

I'm attempting to connect to a local instance of SQL Server running on my machine. I am able to connect to a local instance with this code from our server, but it fails on my local machine.
I've enabled named pipes and all the ips in the SQL Server configuration.
The code I'm using is as follows:
from pymssql import connect
server = r'.\SQLEXPRESS2014' # I've also tried MORGANT-PC\SQLEXPRESS and SQLEXPRESS2014
username = 'MyUserName'
password = 'MyPassword'
master_database_name = 'SuperSecretDatabase'
port = 5000
server_args = {'host': server, 'user': username, 'password': password,
'database': master_database_name, 'port': port} # I've tried having the first key be both host and server, because pymssql's docs are unclear on the difference.
master_database = connect(**server_args)
If I use the instance name, I get this error:
pymssql.InterfaceError: Connection to the database failed for an unknown reason.
I set the port to 5000 so that I could try connecting to it with
server = 127.0.0.1
port = 5000
which fails with the slightly different error message:
pymssql.OperationalError: (20009, b'DB-Lib error message 20009, severity 9:\nUnable to connect: Adaptive Server is unavailable or does not exist\nNet-Lib error during Unknown error (10035)\n')
I've read a bunch of answers here on SO, and most of them seem to indicate it's an issue with FreeTDS, but I'm on Windows 8.1, so I don't have FreeTDS.
I've tried connecting with sqlcmd with the host\instance name and that works fine. It also works in SSMS.
I've tried passing .\SQLEXPRESS2014 to both the host and server parameter in pymssql.connect() and they both fail with the same aforementioned error.
I briefly tried using adodbapi, but I'm getting exactly the same error messages.

The solution ended up being a combination of things.
I needed to disable all IPs other than 127.0.0.1.
I needed to create C:\freetds.conf with the following text:
[global]
port = 1433
tds version = 7.0
I needed to change the account my SQL instance logs in with to LocalSystem.

Yes, 1433 s the default.
This works fine for me:
library(RODBC)
dbconnection <- odbcDriverConnect("Driver=ODBC Driver 11 for SQL Server;Server=server_name; Database=db_name;Uid=; Pwd=; trusted_connection=yes")
initdata <- sqlQuery(dbconnection,paste("select * from MyTable;"))
odbcClose(channel)

Try connecting on the default SQL server port, which is 1433, not 5000.
And check that you can connect to the correct instance using SQL mgmt studio.

I had a similar issue, with the following error:
_mssql.MSSQLDatabaseException: (18456, b"Login failed for user
'script_svc'.DB-Lib error message 20018, severity 14:\nGeneral SQL Server
error: Check messages from the SQL Server\nDB-Lib error message 20002,
severity 9:\nAdaptive Server connection failed\n")
The user I had established was a local user on the machine.
The solution for me was putting ".\" in front of the username and it then recognized it as a local user and allowed the query to work.
Your results may vary.. but I thought I would mention it.

Have you tried using pyodbc instead?
import pyodbc
cnxn = pyodbc.connect('DRIVER={ODBC Driver 13 for SQL Server};SERVER=SERVERNAME;DATABASE=testdb;UID=me;PWD=pass')
cursor = cnxn.cursor()
cursor.execute("select user_id, user_name from users")
rows = cursor.fetchall()
for row in rows:
print row.user_id, row.user_name
Don't forget to add the ODBC driver to your Windows. Go to: Control Panel > Systems and Security > Administrative Tools > ODBC Data Sources
Either the 32-bit or 64-bit version depending on your computer.
Then you click on the System DNS file. If you do not see any MySQL driver you have to click ADD. It brings up a list, from that list select the MySQL driver.
For me, it was ODBC Driver 13 for SQL Server. Click finish. Once you do that then you have to change your connection line in your code to the corresponding Driver that you just filled out.
Source: pyodbc + MySQL + Windows: Data source name not found and no default driver specified

Ident connection fails via psycopg2 but works via command line

When I try to connect to my postgres server via psycopg2 with a bit of code like this (running python as "username"):
psycopg2.connect(database="apis_master")
I get an error
psycopg2.OperationalError: FATAL: Ident authentication failed for user "username"
But when I run psql straight from the command line (as user "username") like so:
psql -d apis_master
I connect with no problem.
I can't see what is different between these two connection methods. Am I missing some configuration option with psycopg2?

Your command line user and your python user are different. When you instantiate psycopg2 object, pass user credentials:
db = psycopg2.connect(
host = 192.168.0.1, # example IP, use 'localhost' if local, otherwise the IP of the server where Postgre is located.
database = 'apis_master'
user = 'my_db_user',
password = 'my_db_password'
)
This should solve your connection problem.

The problem was that there were two PGSQL instances running on this system. One was 8.4 and not configured to ident with my username, the other was 9.1 and had my username. Command line psql was automatically picking 9.1 running on a non-standard port while psycopg2 was using the default port. Specifying the port in the psycopg2 connection line fixed the problem.

How to connect to remote mysql server in python

Hi i have a requirement where i need to connect to remote mysql server. My application shall be running on local machine and my mysql will be running on remote server.I have tried the following code:
DB = 'gts'
DB_HOST = 'ps95074.dreamhost.com'
DB_USER = 'root'
DB_PASSWORD = 'dbadminpassword'
conn = MySQLdb.Connection(db=DB, host=DB_HOST, user=DB_USER,passwd=DB_PASSWORD)
cursor = conn.cursor()
But i am getting the following error
OperationalError: (2005, "Unknown MySQL server host 'ps95074.dreamhost.com' (1)")
Instead if i use
DB_HOST='localhost'
Everything works fine. How can same be possible with remote host.Any help shall be appreciated.

Check your firewall. That server is online and available from any machines:
> mysql -h ps95074.dreamhost.com
ERROR 1045 (28000): Access denied for user 'myuser'#'myhost' (using password: NO)
However, even if you can connect chances are good that your database user only allows local connections.
Update: I just tried it again and now it also fails using the commandline client. So clearly something is wrong with your server.

python mysql connection problem

This code works fine:
import MySQLdb
db = MySQLdb.connect("localhost", "root", "","bullsorbit")
cursor = db.cursor()
cursor.execute("Select * from table where conditions'")
numrows = int(cursor.rowcount)
print 'Total number of Pages : %d ' % numrows
but if I give my IP address
db = MySQLdb.connect("192.168.*.*", "root", "","bullsorbit")
it will give this error
super(Connection, self).__init__(*args, **kwargs2)
_mysql_exceptions.OperationalError: (2003, "Can't connect to MySQL server on 'ip address' (111)")

Code 2003 is a standard MySQL client error:
Error: 2003 (CR_CONN_HOST_ERROR) Message: Can't connect to MySQL server on '%s' (%d)
I'd guess that your user is not allowed to connect to the MySQL server using an iP-address. What happens if you try a connection usign the MySQL commandline client?
$ mysql --host=192.168.1.1 -u root bullsorbit

with localhost you connect via loopback-interface.
with ip-addr you connect - as you connect from extern.
if your server allows only the local (loopback) connection
your ip-addr connection fails. (security!)
look at your mysql config, maybe only local-connections are allowed.
is the skip-networking switch off (in the mysql-conf) ?
#skip-networking

For the 2003 error, another possibility is that too many connections are being attempted in too short of time. I noticed this same behavior when I had 127.0.0.1 as my connect string. First I replaced it with localhost which got me further but still the same 2003 error. Then I saw that if I scaled back the number of calls the error disappeared completely.

Instead of:
db = MySQLdb.connect("192.168..", "root", "","bullsorbit")
try:
db = MySQLdb.connect(user="root", host="192.168..", db="bullsorbit")
Password will default to empty string and try the usual identity methods. Host will also default to localhost on default port.