Quality Center - Query the defects linked for a Release folder

PROBLEM:
You wanted to know all the defects logged for particular Release (Release Folder).
Then you wanted to know the defect count that has (at least) linked to one or more testing items.

SOLUTION:
You need 3 tables (Release, Bug, and Release_Folders)

Query:
SELECT COUNT(BG.BG_BUG_ID)
FROM BUG BG, RELEASE_FOLDERS RF, RELEASES R
WHERE RF.RF_NAME = '5.0.0.0'
AND R.REL_PARENT_ID = RF.RF_ID
AND BG.BG_DETECTED_IN_REL = R.REL_ID
AND BG.BG_BUG_ID IN (SELECT LINK.LN_BUG_ID FROM LINK)