使用 Python 连接到 db2 数据库

Question

I'm working on an app that needs to connect to an ibm db2 database. Using DBeaver I can successfully connect to the database (I provide him the db2cc.jar and db2cc4.jar files).

It looks to me as DBeaver is using my Window's credentials to login, because I didn't need to input any login or password to connect.

Now, I've been trying to connect to the same database using python 3.7 and pypi's latest version of the ibm_db package. I didn't install anything else.

import ibm_db

# ...
connection_string = "DATABASE=" + self.params['schema'] + ";" + \
                                         "HOSTNAME=" + self.params['host'] + ";" + \
                                         "PORT=" + self.params['port'] + ";" + \
                                         "PROTOCOL=TCPIP;" + \
                                         "SECURITYMECHANISM=4;" + \
                                         "UID=" + self.params['user'] + ";" + \
                                         "PWD=" + self.params['password'] + ";"


try:
    self.connection = ibm_db.connect(connection_string, "", "")
    # ...

Using my Windows credentials in the parameters, I get the following error message:

Connection error
Bad credentials
SQLCODE=-30082
08001

From what I've seen on stack overflow connecting to a db2 database is complicated...

Does someone know how to connect ? Using the windows credentials or otherwise...

Thanks !

Answer 1

Try the following connection string, If your db2 client and server are on the same host. Change the 'mydb' and 'DB2' (db2 instance name, you can get it with db2ilist utility) constants according your case.

ibm_db.connect('DATABASE=mydb;Instance=DB2;PROTOCOL=IPC;', '', '')

Answer 2

Db2 works fine with Python.

You need to be aware of some basics before you start such as:

• what operating-system runs the target Db2-database and
• what kind of client is being used (java, odbc/cli, .net etc), and
• what kind of authentication/encrpytion is in place for the database (ssl, server based authentication/+/-/encryption etc.).
• is the remote database rdbms Apache DERBY or Db2.

Find out these basics before you start. You have to speak with people who run the Db2-server.

Note: in your question you mention ( SecurityMechanism=4 ) com.ibm.db2.jcc.DB2BaseDataSource.USER_ONLY_SECURITY - this is not relevant for non-JAVA clients, it is relevant is the database manager is DERBY .

For python, the ibm_db package is not a java application.

DBeaver is a java application (hence it uses db2jcc.jar or db2jcc4.jar and a licence-file to connect to the remote database).

You can only use your Windows credentials for connecting to a Db2-database when that Db2-database run on Microsoft-Windows, and the credentials work on the hostname running the Db2-server. For any other combinations, the administrator must issue you a userid/password that is relevant for the target hostname.

The ibm_db package needs a Db2-client to be installed. The Db2-client is a separate installable. There are different kinds of Db2-client depending both on which operating-system runs your Db2-server and how much functionality you need to have in your Db2-client. If your remote Db2-server runs on Linux, Unix, Windows or Z/OS then you can use the "IBM Data Server Runtime Client" which you can either download from IBM's passport advantage website, or get from your internal IT folks. If your Db2-server runs on i-Series (AS/400) you should get its drivers from your i-Series administrator. For either Z/OS or i-Series you will additionally need a license file (which costs money) and you should get that from your administrator, unless your company uses a gateway product called Db2-connect in which case you don't need a separate license file on your workstation.

Answer 3

add ibm_db library and import ibm_db on top in the .py file.

def get_db_connection():
    """
This will help to get db2 connection for query execution
    :return: conn
    """
    dsn_driver = "{IBM DB2 ODBC DRIVER}"
    dsn_database = "BLUDB"
    dsn_hostname = "your_hostname"
    dsn_port = "50000"
    dsn_protocol = "TCPIP"
    dsn_uid = "your_userid"
    dsn_pwd = "your_pwd"
    dsn = (
        "DRIVER={0};"
        "DATABASE={1};"
        "HOSTNAME={2};"
        "PORT={3};"
        "PROTOCOL={4};"
        "UID={5};"
        "PWD={6};").format(dsn_driver, dsn_database, dsn_hostname, dsn_port, dsn_protocol, dsn_uid, dsn_pwd)
    try:
        conn = ibm_db.connect(dsn, "", "")
        print("Connected!")
        return conn
    except Exception:
        print("\nERROR: Unable to connect to the \'" + dsn_database + "\' server.")
        print("error: ", ibm_db.conn_errormsg())
        exit(-1)

function get_db_connection() will return the connection object. On that connection object you can perform operation like:

conn = get_db_connection()
list_results = []
select_query = 'SELECT  a.STATUS,  a.ID  FROM  "TABLE_NAME" AS a'
print(select_query)
selectStmt = ibm_db.exec_immediate(conn, select_query)
while ibm_db.fetch_row(selectStmt) != False:
    list_results.append(ibm_db.result(selectStmt, 'ID'))
ibm_db.close(conn)