Primavera P6 Version 7 comes with Oracle 10g Express Edition, and when you install Primavera P6.7 using Standalone option, Oracle 10g Express is automatically installed. But I found a lot of people have problem getting Oracle working with Primavera P6. One of problem is the configuration of Oracle Instantclient. Here is my experience of configuring Oracle Instantclient.
First, you need to download a 32 bit Oracle instantclient even you are installing Primavera in a 64 bit operating system like Windows 7 or Windows Server 2008 R2. The url is http://www.oracle.com/technology/software/tech/oci/instantclient/index.html. After download, unzip this file in folder in your local drive, i.e. c:\instantclient_10.2, then add this folder to the PATH system environment variable from the advanced settings in the Properties of My Computer.
You don't need to configure the tnsnames.ora file, but in case, your Oracle Connection String must use Oracle Easy Connection format like //mymachine.mydomain:port/XE or mymachine.mydomain:port/XE, for example, enter connection string as 192.168.0.10:1521/XE.
If you opt to use tnsnames.ora, the content of this file should look like below:
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1521))
(SID = XE)
(SERVER = DEDICATED)
Then, add TNS_ADMIN to your Windows environment variables, the value of TNS_ADMIN is the path to your Oracle Instantclient, i.e. c:\instantclient_10.2, finally restart your Windows. After that, when Primavera prompts for the oracle Connection String, just enter XE. If you don't configure oracle Instantclient properly, the typical error you got is this one:
Bad public user name or password. database server error: ORA-12154: TNS:could not resolve the connect identifier specified.
For more information about Instantclient ,please check http://download.oracle.com/docs/cd/B19306_01/server.102/b14357/ape.htm.