FROM_MICROSECOND

Description

The FROM_MICROSECOND function is used to convert a Unix timestamp (in microseconds) to a DATETIME type date-time value. The reference time for Unix timestamps is 1970-01-01 00:00:00 UTC, and this function converts the input microseconds to the corresponding specific date and time after that reference time (including the fractional part of seconds, accurate to microseconds).

Syntax

FROM_MICROSECOND(<unix_timestamp>)

Parameters

Parameter	Description
<unix_timestamp>	Input Unix timestamp, of integer type (BIGINT), representing the number of microseconds from 1970-01-01 00:00:00 UTC

Return Value

Returns a DATETIME type value representing the result of converting the UTC timezone unix timestamp to the current timezone time

• If <unix_timestamp> is NULL, the function returns NULL.
• If the input <unix_timestamp> can be converted to integer seconds, the result returns datetime without scale; if not, the result returns datetime with scale
• If <unix_timestamp> is less than 0, returns an error
• If the returned datetime exceeds the maximum time 9999-12-31 23:59:59, returns an error

Examples

---Current machine is in East 8th timezone, so the returned time is 8 hours ahead of UTC
SELECT FROM_MICROSECOND(0);
+----------------------------+
| FROM_MICROSECOND(0)        |
+----------------------------+
| 1970-01-01 08:00:00.000000 |
+----------------------------+

---Convert 1700000000000000 microseconds added to reference time to datetime
SELECT FROM_MICROSECOND(1700000000000000);

+------------------------------------+
| from_microsecond(1700000000000000) |
+------------------------------------+
| 2023-11-15 06:13:20                |
+------------------------------------+

-- Timestamp contains non-integer seconds (1700000000 seconds + 123456 microseconds)
select from_microsecond(1700000000123456) as dt_with_micro;

+----------------------------+
| dt_with_micro              |
+----------------------------+
| 2023-11-15 06:13:20.123456 |
+----------------------------+

---Input negative number, returns error
 select from_microsecond(-1);
ERROR 1105 (HY000): errCode = 2, detailMessage = (10.16.10.3)[E-218]Operation from_microsecond of -1 out of range


---Input NULL, returns NULL
select from_microsecond(NULL);
+------------------------+
| from_microsecond(NULL) |
+------------------------+
| NULL                   |
+------------------------+

---Exceeds maximum time range 9999-12-31 23:59:59, returns error
select from_microsecond(999999999999999999);
ERROR 1105 (HY000): errCode = 2, detailMessage = (10.16.10.3)[E-218]Operation from_microsecond of 999999999999999999 out of range