ST_trajAttrsAsText-AnalyticDB(AnalyticDB)-阿里云帮助中心

Returns an array of values for a text-type attribute field of a trajectory object.

Syntax

text[] st_trajAttrsAsText(trajectory traj, text attr_name);

Parameters

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

Examples

All three examples use the same trajectory object. The trajectory has two leaf points and includes attributes of various types: velocity (integer), speed (float), angle (string), tngel2 (timestamp), and bearing (bool).

Example 1: Retrieve values of a string attribute

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_trajAttrsAsText(a, 'angle') from traj;
 st_trajattrsastext
--------------------
 {test,NULL}
(1 row)

Example 2: Retrieve values of a timestamp attribute

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_trajAttrsAsText(a, 'tngel2') from traj;
      st_trajattrsastext
------------------------------
 {"2010-01-01 12:30:00",NULL}
(1 row)

Example 3: Retrieve values of a bool attribute

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_trajAttrsAsText(a, 'bearing') from traj;
 st_trajattrsastext
--------------------
 {NULL,t}
(1 row)