ST_trajAttrsAsDouble-PolarDB(PolarDB)-阿里云帮助中心

Returns the values of a double-type attribute field from a trajectory object as a float8[] array.

Syntax

float8[] st_trajAttrsAsDouble(trajectory traj, text attr_name);

Parameters

Parameter	Description
`traj`	The trajectory object.
`attr_name`	The name of the attribute field.

Examples

WITH traj AS (
  SELECT '{"trajectory":{"version":1,"type":"STPOINT","leafcount":2,"start_time":"2010-01-01 11:30:00","end_time":"2010-01-01 12:30:00","spatial":"SRID=4326;LINESTRING(1 1,3 5)","timeline":["2010-01-01 11:30:00","2010-01-01 12:30:00"],"attributes":{"leafcount":2,"velocity":{"type":"integer","length":4,"nullable":true,"value":[1,null]},"speed":{"type":"float","length":8,"nullable":true,"value":[null,1.0]},"angle":{"type":"string","length":64,"nullable":true,"value":["test",null]},"tngel2":{"type":"timestamp","length":8,"nullable":true,"value":["2010-01-01 12:30:00",null]},"bearing":{"type":"bool","length":1,"nullable":true,"value":[null,true]}}}}'::trajectory a)
SELECT st_trajAttrsAsDouble(a, 'velocity') FROM traj;

Output:

 st_trajattrsasdouble
----------------------
 {1,NULL}
(1 row)