ST_nearestApproachDistance-ApsaraDB RDS(RDS)-阿里云帮助中心

Returns the minimum distance between two trajectory objects at their closest point of approach. Optionally, restrict the calculation to a specific time window.

Syntax

float8 ST_nearestApproachDistance(trajectory traj,  trajectory traj2);
float8 ST_nearestApproachDistance(trajectory traj,  trajectory traj2, tsrange range);
float8 ST_nearestApproachDistance(trajectory traj,  trajectory traj2, timestamp t1, timestamp t2);

Parameters

Parameter name	Description
traj1	Trajectory object 1.
traj2	Trajectory object 2.
t1	The start time.
t2	The end time.
range	The time range.

Example

The following example retrieves two trajectories from traj_table and returns the minimum distance between them between 13:00 and 14:00 on January 1, 2010.

Select ST_nearestApproachDistance((Select traj from traj_table where id=1), (Select traj from traj_table where id=2), '2010-1-1 13:00:00', '2010-1-1 14:00:00');