How to validate dates in Hash format in MySQL or C++ - c++

Question

I need to validate dates in Hash (SHA256) format in MySQL or C++.
For example: date1 < date2 or date1 > date2.
I have this query in MySQL:
SELECT SHA1(CURDATE()) -->'2017-09-06'
and:
SELECT SHA1('2017-09-06') --> '34152f3661d73490ac89b0fe15cb3170aac06bb8'
SELECT SHA1('2017-09-07') --> '0b10f03fb245a6486d6ab5b25a2f050bf87093a5'
But, if I use:
SELECT IF (SHA1('2017-09-06') <= SHA1('2017-09-07') ,'True','False') AS Test;
the result is False, therefore, incorrect!

Answer 1

Don't know why you'd do this, but here's a solution for you.
Here's some assumptions.
You were given two date hashes (two inputs)
You know exactly how the date hashes were created (EG: always in the format of YYYY-MM-DD)
You know the range of your target date (So you can reverse the hash back to the original date)
So in psudocode, you'd do something like this.
date getDateFromHash(string inputHash) {
date startDate = '1911-01-01';
date endDate = '2017-12-31';
for(date checkDate = startDate; checkDate < endDate; checkDate + 1 day) {
if (sha1(checkDate) = inputHash) { return checkDate }
}
return null;
}
date firstDate = getDateFromHash("0b10f03fb245a6486d6ab5b25a2f050bf87093a5"); // 2017-09-07
date secondDate = getDateFromHash("34152f3661d73490ac89b0fe15cb3170aac06bb8"); // 2017-09-06
if (firstDate > secondDate) {
return true;
} else {
return false;
} // compare using default date operators
But honestly speaking, like the comment says, there's no point of hashing date values. Hence why I'm only dropping a quich psudo code for you just to point you in the right direction, if you seriously want to tread down this path.