How can I access Oracle from Python? I have downloaded a cx_Oracle msi installer, but Python can't import the library.
I get the following error:
import cx_Oracle
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
import cx_Oracle
ImportError: DLL load failed: The specified module could not be found.
I will be grateful for any help.
Here's what worked for me. My Python and Oracle versions are slightly different from yours, but the same approach should apply. Just make sure the cx_Oracle binary installer version matches your Oracle client and Python versions.
My versions:
Python 2.7
Oracle Instant Client 11G R2
cx_Oracle 5.0.4 (Unicode, Python 2.7, Oracle 11G)
Windows XP SP3
Steps:
Download the Oracle Instant Client package. I used instantclient-basic-win32-11.2.0.1.0.zip. Unzip it to C:\your\path\to\instantclient_11_2
Download and run the cx_Oracle binary installer. I used cx_Oracle-5.0.4-11g-unicode.win32-py2.7.msi. I installed it for all users and pointed it to the Python 2.7 location it found in the registry.
Set the ORACLE_HOME and PATH environment variables via a batch script or whatever mechanism makes sense in your app context, so that they point to the Oracle Instant Client directory. See oracle_python.bat source below. I'm sure there must be a more elegant solution for this, but I wanted to limit my system-wide changes as much as possible. Make sure you put the targeted Oracle Instant Client directory at the beginning of the PATH (or at least ahead of any other Oracle client directories). Right now, I'm only doing command-line stuff so I just run oracle_python.bat in the shell before running any programs that require cx_Oracle.
Run regedit and check to see if there's an NLS_LANG key set at \HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE. If so, rename the key (I changed it to NLS_LANG_OLD) or unset it. This key should only be used as the default NLS_LANG value for Oracle 7 client, so it's safe to remove it unless you happen to be using Oracle 7 client somewhere else. As always, be sure to backup your registry before making changes.
Now, you should be able to import cx_Oracle in your Python program. See the oracle_test.py source below. Note that I had to set the connection and SQL strings to Unicode for my version of cx_Oracle.
Source: oracle_python.bat
#echo off
set ORACLE_HOME=C:\your\path\to\instantclient_11_2
set PATH=%ORACLE_HOME%;%PATH%
Source: oracle_test.py
import cx_Oracle
conn_str = u'user/password#host:port/service'
conn = cx_Oracle.connect(conn_str)
c = conn.cursor()
c.execute(u'select your_col_1, your_col_2 from your_table')
for row in c:
print row[0], "-", row[1]
conn.close()
Possible Issues:
"ORA-12705: Cannot access NLS data files or invalid environment specified" - I ran into this before I made the NLS_LANG registry change.
"TypeError: argument 1 must be unicode, not str" - if you need to set the connection string to Unicode.
"TypeError: expecting None or a string" - if you need to set the SQL string to Unicode.
"ImportError: DLL load failed: The specified procedure could not be found." - may indicate that cx_Oracle can't find the appropriate Oracle client DLL.
You can use any of the following way based on Service Name or SID whatever you have.
With SID:
import cx_Oracle
dsn_tns = cx_Oracle.makedsn('server', 'port', 'sid')
conn = cx_Oracle.connect(user='username', password='password', dsn=dsn_tns)
c = conn.cursor()
c.execute('select count(*) from TABLE_NAME')
for row in c:
print(row)
conn.close()
OR
With Service Name:
import cx_Oracle
dsn_tns = cx_Oracle.makedsn('server', 'port', service_name='service_name')
conn = cx_Oracle.connect(user='username', password='password', dsn=dsn_tns)
c = conn.cursor()
c.execute('select count(*) from TABLE_NAME')
for row in c:
print(row)
conn.close()
Here is how my code looks like. It also shows an example of how to use query parameters using a dictionary. It works on using Python 3.6:
import cx_Oracle
CONN_INFO = {
'host': 'xxx.xx.xxx.x',
'port': 12345,
'user': 'SOME_SCHEMA',
'psw': 'SECRETE',
'service': 'service.server.com'
}
CONN_STR = '{user}/{psw}#{host}:{port}/{service}'.format(**CONN_INFO)
QUERY = '''
SELECT
*
FROM
USER
WHERE
NAME = :name
'''
class DB:
def __init__(self):
self.conn = cx_Oracle.connect(CONN_STR)
def query(self, query, params=None):
cursor = self.conn.cursor()
result = cursor.execute(query, params).fetchall()
cursor.close()
return result
db = DB()
result = db.query(QUERY, {'name': 'happy'})
import cx_Oracle
dsn_tns = cx_Oracle.makedsn('host', 'port', service_name='give service name')
conn = cx_Oracle.connect(user='username', password='password', dsn=dsn_tns)
c = conn.cursor()
c.execute('select count(*) from schema.table_name')
for row in c:
print row
conn.close()
Note :
In (dsn_tns) if needed, place an 'r' before any parameter in order to address any special character such as '\'.
In (conn) if needed, place an 'r' before any parameter in order to address any special character such as '\'. For example, if your user name contains '\', you'll need to place 'r' before the user name: user=r'User Name' or password=r'password'
use triple quotes if you want to spread your query across multiple lines.
Note if you are using pandas you can access it in following way:
import pandas as pd
import cx_Oracle
conn= cx_Oracle.connect('username/pwd#host:port/service_name')
try:
query = '''
SELECT * from dual
'''
df = pd.read_sql(con = conn, sql = query)
finally:
conn.close()
df.head()
In addition to the Oracle instant client, you may also need to install the Oracle ODAC components and put the path to them into your system path. cx_Oracle seems to need access to the oci.dll file that is installed with them.
Also check that you get the correct version (32bit or 64bit) of them that matches your: python, cx_Oracle, and instant client versions.
In addition to cx_Oracle, you need to have the Oracle client library installed and the paths set correctly in order for cx_Oracle to find it - try opening the cx_Oracle DLL in "Dependency Walker" (http://www.dependencywalker.com/) to see what the missing DLL is.
Ensure these two and it should work:-
Python, Oracle instantclient and cx_Oracle are 32 bit.
Set the environment variables.
Fixes this issue on windows like a charm.
If you are using virtualenv, it is not as trivial to get the driver using the installer. What you can do then: install it as described by Devon. Then copy over cx_Oracle.pyd and the cx_Oracle-XXX.egg-info folder from Python\Lib\site-packages
into the Lib\site-packages from your virtual env. Of course, also here, architecture and version are important.
import cx_Oracle
from sshtunnel import SSHTunnelForwarder
# remote server variables
remote_ip_address = "<PUBLIC_IP_ADDRESS_OF_DB_SERVER>"
remote_os_username = "<OS_USERNAME>"
ssh_private_key = "<PATH_TO_PRIVATE_KEY>"
# Oracle database variables
database_username = "<DATABASE_USER>"
database_password = "<DATABASE_USER_PASSWORD>"
database_server_sid = "<ORACLE_SID>"
def server_connection():
server = SSHTunnelForwarder(
remote_ip_address,
ssh_username=remote_os_username,
ssh_password=ssh_private_key,
remote_bind_address=('localhost', 1521) # default Oracle DB port
)
return server
def database_connection():
data_source_name = cx_Oracle.makedsn("localhost",
server.local_bind_port,
service_name=database_server_sid)
connection = cx_Oracle.connect(database_username,
database_password,
data_source_name,
mode=cx_Oracle.SYSDBA) # If logging in with SYSDBA privs,
# leave out if not.
return connection
def database_execute():
connection = database_connection()
cursor = connection.cursor()
for row in cursor.execute("SELECT * FROM HELLO_WORLD_TABLE"):
print(row)
if __name__ == '__main__':
server = server_connection()
server.start() # start remote server connection
connection = database_connection() # create Oracle database connection
database_execute() # execute query
connection.close() # close Oracle database connection
server.stop() # close remote server connection
If you're accessing the Oracle database via a bastion tunnel, you just need to modify this piece of code:
def server_connection():
server = SSHTunnelForwarder(
remote_ip_address, # public IP of bastion server
ssh_username=remote_os_username,
ssh_password=ssh_private_key,
remote_bind_address=('localhost', 1521),
local_bind_address=('0.0.0.0', 3333) # Suppose local bind is '3333'
)
return server
Related
I am using this code to connect with oracle database:
import cx_Oracle
conn_str = u"jbdc:oracle:thin:#****_***.**.com"
conn = cx_Oracle.connect(conn_str)
c = conn.cursor()
However, I am getting this error:
ORA-12560: TNS:protocol adapter error
How can I resolve it?
Thank you
You cannot use a JDBC thin connect string to connect with cx_Oracle (or the new python-oracledb). You must use either an alias found in a tnsnames.ora file, or the full connect descriptor (such as that found in a tnsnames.ora) file or an EZ+ Connect string. An example follows:
conn_str = "user/password#host:port/service_name"
With the new python-oracledb driver you can also do this:
import oracledb
conn = oracledb.connect(user="USER", password="PASSWORD", host="my_host",
port=1521, service_name="my_service")
See the documentation for more details.
I am using python's pyodbc library to connect with the Oracle Database. The authentication to my non-prod servers were set-up as Basic Authentication so my connection string worked well.
It was tough to understand and set up the right drivers initially, But then did manage to get through. Here is what the code looks like for connection and worked well for my other servers.
import textwrap
import pyodbc
connection_string = textwrap.dedent('''Driver={driver};
DBQ={hostname}:{port}/{sid};
UID={username};
PWD={password};
Connection Timeout=30;
Trusted_Connection="yes"
'''.format(driver = 'Oracle in instantclient_11_2',
hostname = <hostname>,
port = <port>,
sid = <sid>,
username = <username>,
password = <passwd>
))
connection = pyodbc.connect(connection_string)
To my surprise PROD is authenticated via LDAP only. To which I have the LDAP Server, Context, and DB Service along with the credentials.
I tried creating my connection string as
connection_string = textwrap.dedent('''Driver={driver};
DBQ={hostname}:{port}/{sid};
UID={username};
PWD={password};
Connection Timeout=30;
Authentication=LDAP;
Trusted_Connection="yes"
'''.format(driver = 'Oracle in instantclient_11_2',
hostname = <ldap_server>,
port = 389,
sid = <db_service>,
username = <username>,
password = <passwd>
))
To which I was not surprised to know it wont work. Tried going through many links but could not get through. Has anyone tried this before or please let me know what I must be missing.
I could definitely connect in SQL Developer using the LDAP Authentication. And since TNS Listener is not configured on this server I cannot use Basic Authentication to connect.
And help would be welcome on this.
Setting up Oracle Drivers - (This is a pre-requisite if exist please ignore)
Download Oracle Instant Client for Microsoft Windows (x64) 64-bit. Alternatively download available for your 32 bit system.
Choose your version of Oracle Database. My version was 11.2.0.4.0
Download below files -
i. Instant Client Package - Basic
ii. Instant Client Package - ODBC
Unzip both the packages into the same directory such as C:\oracle\instantclient_19_3.
Execute odbc_install.exe from the Instant Client directory. If Instant Client is 11g or lower, start the command prompt with the Administrator privilege.
Create C:\oracle\instantclient_19_3\network\admin folder to place tnsnames.ora, sqlnet.ora.
Set Environment variable - TNS_ADMIN to above folder location.
Add C:\oracle\instantclient_19_3 to PATH Environment variable.
Add C:\oracle\instantclient_19_3 to ORACLE_HOME (optional, if connection doesn't work try this.)
LDAP Authentication
Create two files: sqlnet.ora and ldap.ora
ldap.ora
# Place this file in the network/admin subdirectory or your
# $ORACLE_HOME location.
# LDAP Server name should be added here. Rest all the values remains unchanged.
DIRECTORY_SERVERS = (your-server.your-organization:389:636)
DEFAULT_ADMIN_CONTEXT = "ldap-ou-designation"
DIRECTORY_SERVER_TYPE = OID
sqlnet.ora
# Place this file in the network/admin subdirectory or your
# $ORACLE_HOME location.
SQLNET.AUTHENTICATION_SERVICES=(NTS)
NAMES.DIRECTORY_PATH = (LDAP)
Verify C:\oracle\instantclient_19_3 is present in the Path else try updating the path in the Python Code as below
import os
lib_dir=r"C:\oracle\instantclient_19_3"
os.environ["PATH"] = lib_dir + ";" + os.environ["PATH"]
With all this set-up in place you should have
username, password and DB Service name lets call it as db_service here
with cx_Oracle
import cx_Oracle
con = cx_Oracle.connect('{0}/{1}#{2}'.format(user, password, db_service))
version_script = "SELECT * FROM v$version"
cursor = con.cursor()
cursor.execute(version_script)
version = cursor.fetchall()
print(version[0][0])
Ouput
-----
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
with pyodbc
import pyodbc
con = pyodbc.connect('Driver={0};DBQ={1};UID={2};PWD={3}'.format(driver, db_service, user, password))
version_script = "SELECT * FROM v$version"
cursor = con.cursor()
cursor.execute(version_script)
version = cursor.fetchall()
print(version[0][0])
Ouput
-----
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
#Drivers for pyodbc
pyodbc.drivers()
Output
------
['ODBC Driver 17 for SQL Server',
'Oracle in instantclient_11_2']
References :
https://www.oracle.com/database/technologies/instant-client/winx64-64-downloads.html
https://www.oracle.com/database/technologies/releasenote-odbc-ic.html
https://eikonomega.medium.com/connecting-to-oracle-database-with-cx-oracle-and-ldap-5da7925a305c
When I try to run the below code I am getting following error. Tried referring other posts but it does not seem to help.
The server principal "{Myuser}" is not able to access the database "{database}" under the current security context. (916) (SQLExecDirectW)'
import pyodbc
cnxn = pyodbc.connect("Driver={SQL Server};"
'Server=XXXXXXX;'
'Port=xxxx'
'Username={service_account}'
'Password={password of service_account}'
'Database={detabase};'
'Trusted_Connection=yes;')
results = cnxn.cursor()
results.execute('SELECT * FROM {database}.dbo.{tablename}')
for row in results:
print(row)
If you are going to use Microsoft's ODBC driver for SQL Server and Trusted_Connection=yes (SQL Server Windows authentication) then you don't pass the Windows credentials in the connection string. Instead, you run your Python app as the Windows user. Ways to do that include
launching the Python app from a Windows command prompt using the RUNAS command, or
Shiftright_clicking your app's icon, then choose "Run as different user".
Another option might be to use the FreeTDS ODBC driver. It supports the older NTLM authentication protocol and allows you to specify the DOMAIN, UID, and PWD (for Windows authentication) in the connection string.
This worked for me:
import pyodbc
password = "<password>"
conn = pyodbc.connect("Driver={SQL Server};Server=<host>;Port=<port>;UID=
<username>;PWD=" + password + ";Database=<dbname>;")
cursor = conn.cursor()
cursor.execute('SELECT * FROM <table>')
for row in cursor:
print(row)
Using Oracle 12cR1 and Python 3.5.
I have Oracle package files in client folders
Below is the package header with path
/fodler1/folder2/pkh/mypkg.sql
Below is the package body with path
/fodler1/folder2/pkb/mypkg.sql
I want to compile mypkg header and body in Oracle using Python script. Below is a modified form of the Python code I used.
import cx_Oracle as ora
conn = ora.connect("myuser/mypwd#myservice")
cur = conn.cursor()
with open("/fodler1/folder2/pkh/mypkg.sql","r") as sqlFile:
sql = sqlFile.read()
cur.execute(sql)
with open("/fodler1/folder2/pkb/mypkg.sql","r") as sqlFile:
sql = sqlFile.read()
cur.execute(sql)
cur.close()
conn.close()
This doesn't seem to work. When I query all_objects in Oracle, the status shows as INVALID. When I compiled the header in Oracle SQL Developer, the header's status alone became VALID. Am I missing something? Is there a better way to achieve my objective?
I have case :
import pymysql
conn = pymysql.connect(host='127.0.0.1', unix_socket='/opt/lampp/var/mysql/mysql.sock', user='root', passwd=None, db='test')
cur = conn.cursor()
cur.execute("test < /mypath/test.sql")
cur.close()
conn.close()
I always get error :
1064 , "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'test < /mypath/test.sql' at line 1"
I tried to use source and it still failed. Did you know why?
Thank you.
Your error message says that the MySQL server can't understand
test < /mypath/test.sql' at line 1
If you're a long time *nix user, it seems intuitive that you should be able to use commands like this to pass various sorts of data streams to various programs. But that's not the way the Python sql API (or most language-specific) sql APIs works.
You need to pass a valid SQL query to the execute() method in the API, so the API can pass it to the database server. A vaild query will be something like INSERT or CREATE TABLE.
Look, the server might be on a different host machine, so telling the server to read from /mypath/test.sql is very likely a meaningless instruction to that server. Even if it did understand it, it might say File test.sql not found.
The mysql(1) command line client software package can read commands from files. Is that what you want?
>>> import MySQLdb
>>> db = MySQLdb.connect(host = 'demodb', user = 'root', passwd = 'root', db = 'mydb')
>>> cur = db.cursor()
>>> cur.execute('select * from mytable')
>>> rows = cur.fetchall()
Install MySQL-Python package to use MySQLdb.