How can we process two files by comparing key fields?

1.	How can we process two files by comparing key fields?
Answer» There are 2 possible APPROACHES for this: APPROACH 1: We can read records from both files, if the key fields match, then they can be ignored. If upon key comparison, the results are unequal, then we identify which FILE has missing or new records and update the file with missing records accordingly. Approach 2: If both files have the same records, then the work will be reduced. If file 1 comes to the AT END state, then we have to move HIGH VALUES into the key field. The same goes to file 2. This process needs to be repeated until both key fields are equal to HIGH VALUES. For this process to work, the key fields should be in PIC(X) format and not numeric. To make the process easier, we can avoid a lot of I-O operations by reading data to the local array table and then processing the records from there.

Answer»

There are 2 possible APPROACHES for this:

APPROACH 1:
- We can read records from both files, if the key fields match, then they can be ignored.
- If upon key comparison, the results are unequal, then we identify which FILE has missing or new records and update the file with missing records accordingly.
Approach 2:
- If both files have the same records, then the work will be reduced.
- If file 1 comes to the AT END state, then we have to move HIGH VALUES into the key field. The same goes to file 2.
- This process needs to be repeated until both key fields are equal to HIGH VALUES.
- For this process to work, the key fields should be in PIC(X) format and not numeric.

To make the process easier, we can avoid a lot of I-O operations by reading data to the local array table and then processing the records from there.

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