This is not the place to ask that question. Use the Information Center to find basic system information. This site is for problem assistance. Tom

And we can’t know why you would need OVRDBF before OPNQRYF because you haven’t shown us your code nor told us what the problem is. Since OVRDBF isn’t required in order to use OPNQRYF, we don’t know why it is needed in your situation. — Tom

Tom is right use the information center.Here is a quick, inaccurate guide to what you read.Opnqryf creates a path to the data.ovrdbf replaces a path used by your application program with another path such as the one created by he opnqryf.Phil

Oh.. But in many articles they telling we need to define OVRDBF before using OPNQRYF. Let me try then i will come here.. Thanks

Certainly the practice is OVRDBF before OPNQRYF but I don’t know if the order matters.  Today we are much more likely to use SQL in the application programs to achieve the same results.

If your use of OPNQRYF requires OVRDBF, then the OVRDBF does need to be before OPNQRYF. If you put it after OPNQRYF, then it won’t be in effect when OPNQRYF executes.
 
That’s always true of OVRDBF. It always must be executed before it is needed. It doesn’t make any difference if you’re using it for OPNQRYF or for some other purpose. OVRDBF is only required with OPNQRYF if your programming needs an override. If it doesn’t need an override, then you don’t need OVRDBF.
 
But we can’t spend our time teaching about what OVRDBF does. That’s what you go to school for, or that’s what the Information Center is for, or that’s what you practice and experiment for. We are all volunteers here. We’re not paid teachers.
 
Unless you actually have a problem, we can’t help.
 
Tom

Thanks Tom..

How can you be so stupid? You do not like what you do?