I have a field bill type id which has suppose x, y and z values. Bill Type ID is a prompt and the condition is when psquery is run and if bill type id value is blank then it should return all the rows with bill type id x,y and z.

Following is the case expression and Decode function written:

(CASE 
WHEN A.BILL_TYPE_ID = ' ' THEN A.BILL_TYPE_ID LIKE ' %' 
ELSE A.BILL_TYPE_ID = :3 
END ))

SELECT 
  C.NAME1, 
  TO_CHAR(A.FROM_DT,'YYYY-MM-DD'), 
  B.LINE_SEQ_NUM,  
  B.IDENTIFIER,  
  B.DESCR,  
  B.GROSS_EXTENDED_AMT,  
  A.INVOICE_AMOUNT, 
  C.SETID, 
  C.CUST_ID 
FROM PS_BI_HDR A, PS_BI_LINE B, PS_CUSTOMER C 
WHERE 
( 
  A.BUSINESS_UNIT = B.BUSINESS_UNIT 
  AND A.INVOICE = B.INVOICE 
  AND A.BILL_TO_CUST_ID = C.CUST_ID 
  AND A.BUSINESS_UNIT = :1 
  AND A.BILL_STATUS = :2 
  AND 
  ( 
    A.BILL_TYPE_ID = 
    (
      CASE 
        WHEN A.BILL_TYPE_ID = ' ' THEN A.BILL_TYPE_ID LIKE ' %' 
        ELSE A.BILL_TYPE_ID = :3 
      END 
    )
  ) 
) ORDER BY 1, 3

With above case expression I am getting error:

Missing Keyword

and I am not able to debug which keyword is missing.

Decode(:3,' ','%',:3)

Using Decode function I am not getting error but when bill type id is blank then it does not return any rows.