Performace : SQL with CASE

Question

Hi,
Why execution plan for SQL1 & SQL2 are same?
Is there any performace impact(as compare to normal select) if we put CASE statement in SQL?
SQL1
SELECT
CASE WHEN PCS_SKEY < 1 then NULL ELSE PCS_SKEY END PCS_SKEY,
CASE WHEN MDT_SKEY < 1 then NULL ELSE MDT_SKEY END MDT_SKEY,
CASE WHEN DLS_SKEY < 1 then NULL ELSE DLS_SKEY END DLS_SKEY,
CASE WHEN MVI_SKEY < 1 then NULL ELSE MVI_SKEY END MVI_SKEY
FROM F_REG
SQL2
SELECT
     PCS_SKEY,
     MDT_SKEY,
     DLS_SKEY,
     MVI_SKEY           
FROM F_REG

Answer 1

Explain Plan
SQL1:
Operation     Object Name     Rows     Bytes     Cost     Object Node     In/Out     PStart     PStop
SELECT STATEMENT Optimizer Mode=ALL_ROWS          4 M          38755                     
TABLE ACCESS FULL     SMMTDW.F_REG     4 M     64 M     38755                     
SQL2:
Operation     Object Name     Rows     Bytes     Cost     Object Node     In/Out     PStart     PStop
SELECT STATEMENT Optimizer Mode=ALL_ROWS          4 M          38755                     
TABLE ACCESS FULL     SMMTDW.F_REG     4 M     64 M     38755