Take Job Design as
Seq.File ------- Tx ------ Ds
Read and load the data in Seq.file
Select first line is column name
And in Transformer stage Create three columns to get the data
You can take columns names as c_id,c_name,c_sal with respective data types.
Write the expression in Derivations to the columns as below
Field (dslink3.customers,',',1) for c_id
Field (dslink3.customers,',',2) for c_name
Field (dslink3.customers,',',3) for c_sal
That's it you will get the data in 3 different columns in the output as required.
After compile and Run the Job.