Shall i use this query to retrieve first 4 records, Select empno, sal from emptbl where empno < 5. like this can we fetch first 100 records?

Select empno, sal from emptbl where empno < 101.By this query can we fetch first 100 recs? where empno is primary key.It won't throw -811 error? if it wont,then what is use of cursor technique while fetching first 100 recs. Please need more clarification.

I have two input files i/p1 name id-key flag date i/p 2 name id-key date if id-key matches in the both the files then it should write the output file from i/p1 with flag 'Y'. It should be done thru JCL sort card ,Please provide the info on this. ---Note : output file should have all records from i/p1 with proper Flag.