The not so easy and instant Oracle Instant Client install.
First
Uninstall any old Oracle drivers.
If you can run the Oracle Installer then run that first and uninstall all Oracle products. Also check Add/Remove programs in Control Panel. Otherwise delete all the Oracle files and remove all references from the Windows Environment (My Computer->Properties->Advanced Tab) especially ORACLE_HOME, TNS_ADMIN and oracle directories in the PATH environment variable.
Download and install the Oracle Instant Client
(Download link at the bottom of this page The actual link seems to change frequently)
Get Instant Client Package – Basic Lite, ODBC, and SQLPlus. Unzip all
to the same directory (e.g. C:\instantclient)
Add this directory to your System PATH and add two new system environment variables ORACLE_HOME and TNS_ADMIN containing the directory.
To add or modify environment variables Right click on “My Computer”, select Properties from the popup. Click the Advanced Tab, Click the “Environment Variables” button. In the lower “System Variables” list you can edit or add new system variables.
Open Control Panel->Administrative Tools->Data Sources(ODBC), Select the system tab. Click Add, Select Oracle in instantclient and click finish. The Oracle ODBC dialog should appear.
Data Source Name: A_Descriptive_Name
TNS Service Name: //hostname_or_ip_address/XE
UserId: scott
Use the defaults for everything else.
Click Test Connection
Password: tiger
Of course replace scott and tiger with your login/password
Your data source is ready to use in Arc, Excel, Access, etc.
ArcGIS setup for the Oracle Database
In ArcCatalog go to Database Connections, Double click on Add OLE DB Connection, select “Microsoft OLE DB Provider for ODBC Drivers”, click next, Select the data source that you created earlier. Enter Username and password, “Check Allow saving password”, click test connection. Click OK then name the connection (this will be already highlighted).
There are other ways to do this, but this works for me. You may ask “Why do they have to make this so hard”: The answer “Because they can”.
