Describe `ROUND(x)` WTFs

[AnyhowStep]

trafficstars

SELECT
ROUND(0.5e0),
ROUND(-0.5e0)

Where the numbers are double precision data types.

It's 0 and 0 on PostgreSQL.

It's 1 and -1 on SQLite

It's 1 and 0 on JS

It's 0 and 0 on MySQL

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But if 0.5 and -0.5 is a DECIMAL on MySQL, then the answer is 1 and -1

But if 0.5 and -0.5 is a DECIMAL on PostgreSQL, then the answer is 1 and -1

[AnyhowStep]

Well, not really a WTF. It's just that there are so many different ways to round numbers.

https://en.wikipedia.org/wiki/Rounding#Round_half_to_even