600 - 500 is not 100

600: legacy accounts


500: all count nung accountinstallment sa new system
200 legacy accounts migrated + 300 new accounts


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mathematically, difference will be 100
600 - 500 = 100

pero yung legacy import lookup, reports 400 in count

600 (legacy)
500 (new)

100 is the supposed difference

pero 400 ang nireport ng query, what could be the problem?


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what could be the likely scenario?

since we're not dealing with plain math numbers here, it's more of a sets scenario, something like set theory or venn diagrams :) how i miss discrete mathematics subject in college, antaas ng grade ko sa subject na to.


typical inquiries like this can provide some hints or explanation about the numbers involve:

"what accounts in Sets of the New system accounts not found in the Sets of the legacy account or vice-versa?"


maaari meron mga accounts na meron sa new system na wala pa sa legacy, so baliktad.


legacy(600 total)

new(500 total) sabihin natin na yung 200 is yung nimigrate from legacy. and yung other 300, is yung new accounts na hindi pa rin na-eencode sa legacy ni rhea(n-b-backlog n rin halimbawa ang main sa encoding ng new accounts)

so yung query like this will not return 100:

SELECT account FROM legacySystem WHERE account NOT IN (SELECT account FROM newSystem)

it will return: 400(not 100)

because: yung actual lng na na-itransfer na legacy papuntang new is 200(not 500)