"Loose" Algorithm for lab 7


use a SORT statement to sort the "master" file
use a SORT statement to sort the "add" file
use a MERGE statement to merge the "master" and "add" files

initialize array

read merged file
repeat until end of merged file
	move input-rec to table to store each record in a 1-dim array
	read merged file
end-repeat
close merged file

read delete file
repeat until end of delete file
    use a SEARCH statement to find the record to delete in the table
    when found, remove record from table
    read delete file
end-repeat
close delete file

set index to 1
repeat until end of table
    if record in table, write it to master file
end-repeat



Some notes:

The object here is to update a master file by applying some adds and deletes. You have a master 
file, add file and delete file. The add file contains patients to add to the master file and the 
delete file contains patients to remove from the master file.

You do not have to worry about trying to add a patient that's already there. You can assume that 
the data is OK.

The MERGE will combine 2 sorted files into one. So that will take care of the adds smoothly.

To do the "delete" function you will load the merged file into a 1 one dimensional table. Each 
element of the table is a copy of the input record. Unlike lab 6, you will load the records into 
the table sequentially (1st record has subscript 1, next one has a subscript of 2, etc.). Maybe a 
PERFORM VARYING until end of file?

Once that's done, you will read the delete file. SEARCH the table looking for a match. If you find a 
match then "remove it" from the table. Don't actually remove it from the table, just set its keys to 
zero or whatever initial value those fields have.

Once you've cycled through the delete file you will then write the remaining records to the file. 
Iterate through the table and if a record is there (keys not the initial value) then write that 
record to the master file (which shouldbe output now).

Don't forget ORGANIZATION IS LINE SEQUENTIAL on all files. It will bite you hard, here, if forgotten.