You can make some more changes (which I don't prefer )
like this,

Code: sql
SELECT PRJ.ID
  FROM PROJECTS   PRJ
     , CU_PROJECT CU
     , PRJ_ASSOC  AS
     , PRJ_UNITS  OBS
     , PRJ_TYPES  TYPE
 WHERE AS.TABLE_NAME = 'PROJECTS'
   AND AS.RECORD_ID  = PRJ.ID
   AND AS.UNIT_ID    = OBS.ID
   AND OBS.TYPE_ID   = TYPE.ID
   AND TYPE.NAME     = 'TEST1'
   AND CU.ID         = PRJ.ID
   AND CU.PRT_CODE   = 'TEST2'