How to get current month records from ORACLE since first date.?

Question

here is my code

SELECT h.ENTERED_DATE,
       d.DENOMINATION,
       sum(h.invoice_total-h.TOTTAL_DISCOUNT)as amount 
  FROM sales_details d
       LEFT JOIN sales_header h 
            ON d.invoice_id=h.invoice_id
 WHERE entered_by='2254'
--HERE IS NEED TO GET DETAILS CURRENT MONTH 1st Date to Sysdate 
GROUP BY 
       ENTERED_DATE,
       d.DENOMINATION
ORDER BY 
       entered_date,
       denomination

• In my application just send only sysdate as parameter. no need to SYSDATE-30. need 1st date to SYSDATE

here shows my two tables sales_header table

sales_details table

Answer 1

try this:

WHERE entered_by='2254'
AND ENTERED_DATE BETWEEN trunc (sysdate, 'mm')/*current month*/ AND SYSDATE

Answer 2

Compare months in where condition

WHERE to_char( sysdate, 'mm' ) = to_char( ENTERED_DATE, 'mm' )

Also

WHERE EXTRACT(month FROM sysdate)=EXTRACT(month FROM ENTERED_DATE)