left join between two tables

What you're looking for doesn't imply a JOIN, it implies EXISTS:

DATA dummy_plant TYPE marc-werks.
SELECT-OPTIONS s_plant FOR dummy_plant.
DATA it_marc TYPE TABLE OF marc.
SELECT * FROM marc
  WHERE marc~werks IN @s_plant
    AND EXISTS (
      SELECT * FROM mseg
      WHERE marc~matnr = mseg~matnr
        AND marc~werks = mseg~werks
        AND mseg~cputm_mkpf >= @sy-uzeit )
 INTO TABLE @it_marc. 

By the way, it seems obvious to me that you should test both CPUTM_MKPF and CPUDT_MKPF:

AND ( mseg~CPUDT_MKPF > @sy-datum
   OR ( mseg~CPUDT_MKPF = @sy-datum
    AND mseg~cputm_mkpf >= @sy-uzeit ) )

NB: I removed CORRESPONDING FIELDS because the target data object has the same structure as the database table.

Hello nick ruju,

You just have to use inner join which is left inner join by default. Error is due to missing @ symbol on all variables used which is the principle while using open SQL statements. Below code for your reference,

select *
from marc
Inner join mseg 
on marc ~ matnr = mseg ~ matnr and marc ~ werks = mseg ~ werks
into CORRESPONDING FIELDS OF TABLE @it_marc
WHERE marc ~ WERKS in @s_plant and mseg ~ CPUTM_MKPF> = @sy-uzeit. .

Regards!