Case When Else In Oracle Sql

I have a query like below, but I got the following error::

> SQL Error [907] [42000]: ORA-00907: missing right parenthesis

Code:

SELECT 
    typ.ID ID, typ.DETAILS DETAILS 
FROM 
    LMP_ORDER_MW_HOST_SVC_TYP typ 
LEFT JOIN 
    LMP_ORDER_MW_HOST_TRX lomht ON typ.ID = lomht.ORDER_SVC_TYP_ID 
WHERE 
    typ.ID IN (CASE 
                   WHEN lomht.ORDER_TRX_ID = :ORDER_TRX_ID 
                       THEN ('31', '21', '51', '45', '35') 
                       ELSE ('12', '13') 
               END);

CASE expressions are really intended to generate new values. Instead, you should just use straight and/or logic in your WHERE clause:

<!-- language: sql -->

SELECT typ.ID ID, typ.DETAILS DETAILS
FROM LMP_ORDER_MW_HOST_SVC_TYP typ
LEFT JOIN LMP_ORDER_MW_HOST_TRX lomht 
    ON typ.ID = lomht.ORDER_SVC_TYP_ID 
WHERE
    lomht.ORDER_TRX_ID = :ORDER_TRX_ID AND
    typ.ID IN ('31', '21', '51', '45', '35') OR
    lomht.ORDER_TRX_ID != :ORDER_TRX_ID AND
    typ.ID ('12', '13');

In SQL, a CASE expression returns a single scalar value (not a comparison or a list of values).

Instead of using a CASE expression, you can use the AND and OR logical operators and brackets for precedence and you need to make sure that you check the equivalent ELSE condition tests for NULL values (because, with trinary logic, NULL is never equal nor not-equal to anything else):

SELECT typ.ID,
       typ.DETAILS
FROM   LMP_ORDER_MW_HOST_SVC_TYP typ 
       LEFT OUTER JOIN LMP_ORDER_MW_HOST_TRX lomht
       ON typ.ID = lomht.ORDER_SVC_TYP_ID 
WHERE  (   lomht.ORDER_TRX_ID = :ORDER_TRX_ID 
       AND typ.ID IN ('31', '21', '51', '45', '35')
       )
OR     (   (  lomht.ORDER_TRX_ID != :ORDER_TRX_ID
           OR lomht.ORDER_TRX_ID IS NULL
           OR :ORDER_TRX_ID      IS NULL
           )
       AND typ.ID IN ('12', '13')
       );