How to Checking INITIAL Values to a Variable or Column in SAP HANA SQL Script?

Hi,

I have to check the INITIAL value of a Variable or a Column in SELECT Query in SAP HANA Procedure or SAP HANA SQL Script.

Can anyone suggest me how to check this.

For Ex:

SELECT *,

      TO_DECIMAL("BREAKDOWNDUR", 12, 0) AS SEC_BREAKDOWNDUR,

      CONCAT(CONCAT(TO_VARCHAR("START_MALFUNCDATE"), ' '), TO_VARCHAR("START_MALFUNCTIME"))

      AS START_TIMESTAMP,

    CONCAT(CONCAT(TO_VARCHAR("END_MALFUNCDATE"), ' '), TO_VARCHAR("END_MALFUNCTIME"))

      AS END_TIMESTAMP

   FROM :SQL_VIQMEL

   WHERE ( START_MALFUNCDATE IS NOT NULL )

   OR    ( ( END_MALFUNCDATE IS NOT NULL )

  AND    ( BREAKDOWNDUR <> 0 ) );

In the above syntax , it's not excluding the rows where START_MALFUNCDATE and END_MALFUNCDATE are having INITIAL Value i.e. 00000000 and BREAKDOWNDUR is a DECIMAL Column and having INITIAL value 0.

Can anyone suggest me how to exclude the rows which are having INITIAL or NULL values.

Thanks in advance.

Regards,

Ramana.