Case expression in the WHERE clause of a delete statment

[sa0309]

I have a delete statement:

My original Delete:
DELETE FROM TableName A
WHERE SCHED_SURGERY_TM >= TRUNC(sysdate)-90


Now I need to delete based upon either START_TM or SCHED_SURGERY_TM :
DELETE FROM TableName A
WHERE
( case
when A.START_TM IS not NULL THEN
A.START_TM >= TRUNC(sysdate)-90
else
A.SCHED_SURGERY_TM >= TRUNC(sysdate)- 90
end
)
What I'm trying to accomplish is use START_TM ( if not null ) else use SCHED_SURGERY_TM and delete the last 90 days of data. I know this example doesn't work. Any suggestions on how this can be accomplished or can it?

Thank you.

 

[SkipVought]

How about...

WHERE 
( case
when [b]NOT[/b] A.START_TM [b]IS NULL[/b] THEN 
A.START_TM >= TRUNC(sysdate)-90 
else 
A.SCHED_SURGERY_TM >= TRUNC(sysdate)- 90
end 
)

Skip,
[sub]
Just traded in my OLD subtlety...
for a NUance![/sub]
"The most incomprehensible thing about the universe is that it is comprehensible" A. Einstein

 

[carp]

Not using case but what about

WHERE (A.START_TM IS not NULL AND A.START_TM >= TRUNC(sysdate)-90)
OR
(A.START_TM IS NULL AND A.SCHED_SURGERY_TM >= TRUNC(sysdate)- 90)