mysql account and users account using exec-program-wait

[SantaYeh]

I store all user account in mysql, and freeradius works fine.
And now, we have some special account that need to write a external
program to do authentication. So we use
the users file using DEFAULT auth-type = Accept with exec-program-wait.
The problem is all mysql accounts doesn't work any more. We check with
radiusd -X and find all mysql accounts
will pass to users and run exec-program-wait.
I just want to know how can we stop the users checking if mysql return OK.

Regards,
Santa Yeh