ST_TimeZone Function Reference for Point Geometry - PolarDB

Returns the IANA time zone name or GMT offset string for a given point.

Syntax

cstring ST_TimeZone(geometry point, boolean timezoneId, integer timezonePrecision);
cstring ST_TimeZone(geography point, boolean timezoneId, integer timezonePrecision);

Parameters

Parameter	Description
`point`	The input point. Must be a point data type with spatial reference system WGS84 (SRID=4326).
`timezoneId`	Controls the output format. `true` (default): returns an IANA time zone name (for example, `Asia/Shanghai`). `false`: returns a GMT offset string (for example, `Etc/GMT+8`).
`timezonePrecision`	The lookup precision. Valid only when `timezoneId` is `true`. `16` (default): ~500 m precision. `21`: ~20 m precision. Use `21` for points near time zone boundaries where a 500 m error could return the wrong time zone.

Return value

Returns a cstring containing the time zone string.

Background

Time zone boundary data comes from the Timezone Boundary Builder project.

Examples

Return an IANA time zone name (default behavior):

SELECT ST_TimeZone('SRID=4326;POINT(121 37)'::geometry);
-- Asia/Shanghai

SELECT ST_TimeZone('POINT(60 37)'::geography);
-- Asia/Tehran

Return a GMT offset string:

SELECT ST_TimeZone('SRID=4326;POINT(121 37)'::geometry, false);
-- Etc/GMT+8

Use higher precision for a point near a time zone boundary:

SELECT ST_TimeZone('SRID=4326;POINT(-121 37)'::geometry, true, 21);
-- America/Los_Angeles

Pass a longitude greater than 180°:

SELECT ST_TimeZone(('SRID=4326;POINT(400 37)'::geometry));
-- Europe/Istanbul