After you launch your application designer, you will prompted for PeopleSoft user id and password. After you enter your credentials you will be displayed with the error message " Missing or invalid version of SQL library PSORA (200,0)" as shown in the below screenshot.
First Reason is "start in" path that you have specified for your application designer is invalid. Application designer use this path to locate the Oracle client bin folder.
Right click on the PSIDE.exe shortcut that you have on your machine. Click on the Properties,you will be displayed with the dialog box. Specify path of the oracle bin folder in "Start in" as highlighted in the below screenshot
Second reason is valid if you are using PeopleTools 8.5x. In this case, your application designer is trying to access 64bit Oracle client library.
PeopleTools 8.5x is certified to run on 64bit windows but the application designer pside.exe is 32bit utility. This means any library that need to be loaded by this 32bit utility has to be 32bit. Due to this you need to make sure Oracle 32bit version is installed in your machine to avoid this error message.
You can identify your Oracle version through the below SQL. This is one of the way.
SELECT * FROM V$VERSION;
The banner will tell you 64-bit if the 64-bit version is installed. If it does not specify 64-bit then it is 32-bit (even though it does not explicitly say so). You will get the same information when using SQL*PLUS.