How to user SQL predicate in a security rule condition

Summary

How to user SQL predicate in a security rule condition

Content

We have a requirement to enable security segment at cost center level. 
One security rule for restricted OU (List of restricted OU are child value kept under a parent OU)- we have used tree structure for that - parent value P50000000 
one rule for non restricted OU - we need to write rule as if values are not in restricted OU parent - IF child values are not in under parent P50000000 
And one rule is for ALL OU 


 what SQL predicate needs to be used for non restricted OU rule condition