How check the jdbc client version in your database?

On the java side you can check the JDBC Client Version very easy.

java -jar ./mwhome/.../ojdbc7.jar -getversion
Oracle 12.1.0.2.0 JDBC 4.1 compiled with JDK7 on Mon_Jun_30_11:30:34_PDT_2014
#Default Connection Properties Resource
#Tue Apr 17 14:13:51 CEST 2018

But somethimes you may not have access to the application server (here Weblogic) or there are many version installed on the application side.
So the best way is to check in you Oracle Database who your client are.

SQL> select SID,NETWORK_SERVICE_BANNER,CLIENT_CHARSET,CLIENT_CONNECTION,CLIENT_VERSION,CLIENT_DRIVER from v$session_connect_info;
       396
Crypto-checksumming service for Linux: Version 12.2.0.1.0 - Production
Unknown                                  Heterogeneous 12.1.0.2.0                               jdbcthin

This is a reliable way to find how (jdbcthin, oci, ..) and with what JDBC Version the client are connecting.

Clone Oracle Home 12c on the same Host

If you have to test some patches and you need a new Oracle Home on the same host, cloning the existing home to the same host is an easy an quick way to do that.

Here a short step by step guide:

  1. check diskspace
    df -h .
  2. copy the oracle home to it’s new location
    cp -rp /opt/app/oracle/product/12.1.0/rdbms6/ /opt/app/oracle/product/12.1.0/rdbms7
  3. export the new home path and cone. this creates as well all nessesary inventory entries. be carefull to use a free oracle_home_name.
    export ORACLE_HOME=/opt/app/oracle/product/12.1.0/rdbms7

    /opt/app/oracle/product/12.1.0 $/opt/app/oracle/product/12.1.0/rdbms6/oui/bin/runInstaller -clone -silent ORACLE_HOME=/opt/app/oracle/product/12.1.0/rdbms7 ORACLE_HOME_NAME="OraDB12Home4" ORACLE_BASE="/opt/app/oracle"

    Starting Oracle Universal Installer...

    Checking swap space: must be greater than 500 MB. Actual 9835 MB Passed
    Preparing to launch Oracle Universal Installer from /tmp/OraInstall2017-11-15_01-14-43PM. Please wait ...
    Copyright (C) 1999, 2014, Oracle. All rights reserved.

    You can find the log of this install session at:
    /opt/app/oraInventory/logs/cloneActions2017-11-15_01-14-43PM.log
    .................................................................................................... 100% Done.

    Setup in progress (Wednesday, November 15, 2017 1:16:34 PM CET)
    .......... 100% Done.
    Setup successful

    Saving inventory (Wednesday, November 15, 2017 1:16:34 PM CET)
    Saving inventory complete
    Configuration complete

    End of install phases.(Wednesday, November 15, 2017 1:17:00 PM CET)
    WARNING:
    The following configuration scripts need to be executed as the "root" user.
    /opt/app/oracle/product/12.1.0/rdbms7/root.sh
    To execute the configuration scripts:
    1. Open a terminal window
    2. Log in as "root"
    3. Run the scripts

    The cloning of OraDB12Home4 was successful.
    Please check '/opt/app/oraInventory/logs/cloneActions2017-11-15_01-14-43PM.log' for more details.

  4. run the root.sh script as instructed.
    /opt/app/oracle/product/12.1.0/rdbms7/root.sh
  5. you can check the inventory if all looks as expected:
    cat /opt/app/oraInventory/ContentsXML/inventory.xml|grep OraDB12Home4

  6. update your oratab and the the OPATCH directories of the database you want to switch to the new home
    /etc/oratab
    ..
    rdbms7:/opt/app/oracle/product/12.1.0/rdbms7:N

    sid rdbms7
    $ORACLE_HOME/OPatch/opatch lsinventory

    create or replace directory OPATCH_INST_DIR as '/opt/app/oracle/product/12.1.0/rdbms7/OPatch';
    create or replace directory OPATCH_SCRIPT_DIR as '/opt/app/oracle/product/12.1.0/rdbms7/QOpatch';
    create or replace directory OPATCH_LOG_DIR as '/opt/app/oracle/product/12.1.0/rdbms7/QOpatch';