Using OR in WHERE CLAUSE in oracle

Some times we will be facing issues in implementing  logic for IF ELSE condition in WHERE CLAUSE in oracle query.

Below is the sample code which shows the work around for it by implementing OR in WHERE CLAUSE

Sample Query:

WITH TEMPTABLE AS (

SELECT EMPLOYEEID,EMPLOYEENAME,DEPARTMENTID

  from EMPLOYEE 

 where EMPSAL=200000)

SELECT EMPLOYEENAME,EMPLOYEEID FROM TEMPTABLE WHERE EMPLOYEESTATUS=1 AND

 (TEMPTABLE.DEPERTMENTID IS NULL or TEMPTABLE.EMPID > 0 AND 

UPPER(TEMPTABLE.EMPLOYEENAME) LIKE UPPER('%TESTUSER%'));