问题
I am trying to use sqlalchemy to connect to an oracle DB. I was expecting the following to work given that it appears the exact syntax is shown in the sqlalchemy documentation.
oracle_db = sqlalchemy.create_engine('oracle://user:pass@server:1521/dev')
but this results in the error:
dsn = self.dbapi.makedsn(url.host, port, **makedsn_kwargs) TypeError: makedsn() takes no keyword arguments
The following call initially works without the service name
oracle_db = sqlalchemy.create_engine('oracle://user:pass@server:1521')
But when trying to connect it fails with an error complaining that the SERVICE_NAME was not provided.
ORA-12504: TNS:listener was not given the SERVICE_NAME in CONNECT_DATA
Oddly this works with cx_Oracle directly:
con = cx_Oracle.connect('user/pass@server:1521/dev')
How am I supposed to connect to the specific service?
Attempts
I have tried to use cx_Oracle.makedsn() explicitly from this question with no luck as well.
Trying to use ? options in the connection string
oracle_db = sqlalchemy.create_engine('oracle://user:pass@server:1521/?sid=dev')
works initially but when I try oracle_db.connect() I get the same ORA-12504 error shown above.
回答1:
Based on the documentation at Sqlalchemy Documentation, you should probably use the cx_oracle engine. The connect string is:
oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
with an option of service_name or sid as follows:
oracle+cx_oracle://user:pass@host:1521/?service_name=hr
oracle+cx_oracle://user:pass@host:1521/?sid=hr
回答2:
Try using this connection string:
engine = create_engine("oracle+cx_oracle://<username>:<password>@(DESCRIPTION = (LOAD_BALANCE=on) (FAILOVER=ON) (ADDRESS = (PROTOCOL = TCP)(HOST = <host>)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = devdb)))")
It worked for me.
来源：https://stackoverflow.com/questions/36455358/python-sqlalchemy-oracle-connection-fails-to-connect-to-sid