SELECT PEA.INCURRED_BY_PERSON_ID AS PERSON_ID, PEA.EXPENDITURE_ENDING_DATE AS WEEK_END_DATE, 
CASE 
  WHEN PEIA.PROJECT_ID IN(496,497,499,502,507) THEN 'V' 
  ELSE PEIA.BILLABLE_FLAG 
  END AS BILLABLE_FLAG, 
NVL(PEIA.QUANTITY,0) AS QUANTITY, 
NVL(PEIA.TRANSACTION_SOURCE, 'EXPENDITURE BATCH') AS TRANSACTION_SOURCE 
FROM
PA_EXPENDITURES_ALL PEA 
INNER JOIN PA_EXPENDITURE_ITEMS_ALL PEIA ON PEA.EXPENDITURE_ID=PEIA.EXPENDITURE_ID 
INNER JOIN APPS.DISC2_GL_WORKING_DAYS period ON  PEIA.EXPENDITURE_ITEM_DATE BETWEEN period.START_DATE AND period.END_DATE;

Operation	Object Name	Rows	Bytes	Cost	Object Node	In/Out	PStart	PStop

SELECT STATEMENT Optimizer Mode=CHOOSE		2 K	 	8285  	 	      	             	 
  HASH JOIN		2 K	161 K	8285  	 	      	             	 
    NESTED LOOPS		2 K	127 K	8007  	 	      	             	 
      VIEW	APPS.DISC2_GL_WORKING_DAYS	1  	20  	52  	 	      	             	 
        SORT GROUP BY		1  	41  	52  	 	      	             	 
          NESTED LOOPS		1  	41  	5  	 	      	             	 
            VIEW	APPS.DISC_GL_MONTH	1  	33  	4  	 	      	             	 
              TABLE ACCESS BY INDEX ROWID	GL.GL_PERIODS	1  	54  	4  	 	      	             	 
                INDEX RANGE SCAN	GL.GL_PERIODS_N1	9  	 	1  	 	      	             	 
                  SORT AGGREGATE		1  	18  	 	 	      	             	 
                    VIEW	APPS.DISC_GL_YEAR	1  	18  	2  	 	      	             	 
                      TABLE ACCESS BY INDEX ROWID	GL.GL_PERIODS	1  	46  	2  	 	      	             	 
                        INDEX RANGE SCAN	GL.GL_PERIODS_N1	2  	 	1  	 	      	             	 
            INDEX RANGE SCAN	APPS.DISC_WEEK_U1	1  	8  	1  	 	      	             	 
      TABLE ACCESS FULL	PA.PA_EXPENDITURE_ITEMS_ALL	2 K	87 K	7955  	 	      	             	 
    TABLE ACCESS FULL	PA.PA_EXPENDITURES_ALL	99 K	1 M	273  	 	      	             	 

SELECT /*+ CARDINALITY(period 100)*/ ....