Syntax:
FROM_UNIXTIME(unix_timestamp[,format])

Returns a representation of unix_timestamp as a datetime or character
string value. The value returned is expressed using the session time
zone. (Clients can set the session time zone as described in
https://dev.mysql.com/doc/refman/8.0/en/time-zone-support.html.)
unix_timestamp is an internal timestamp value representing seconds
since '1970-01-01 00:00:00' UTC, such as produced by the
UNIX_TIMESTAMP() function.

If format is omitted, this function returns a DATETIME value.

If unix_timestamp or format is NULL, this function returns NULL.

If unix_timestamp is an integer, the fractional seconds precision of
the DATETIME is zero. When unix_timestamp is a decimal value, the
fractional seconds precision of the DATETIME is the same as the
precision of the decimal value, up to a maximum of 6. When
unix_timestamp is a floating point number, the fractional seconds
precision of the datetime is 6.

On 32-bit platforms, the maximum useful value for unix_timestamp is
2147483647.999999, which returns '2038-01-19 03:14:07.999999' UTC. On
64-bit platforms running MySQL 8.0.28 or later, the effective maximum
is 32536771199.999999, which returns '3001-01-18 23:59:59.999999' UTC.
Regardless of platform or version, a greater value for unix_timestamp
than the effective maximum returns 0.

format is used to format the result in the same way as the format
string used for the DATE_FORMAT() function. If format is supplied, the
value returned is a VARCHAR.

URL: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html

