catching select query return value in postgresql function and use it - postgresql

Question

I want to execute this function. But it got error said
ERROR:
syntax error at or near ":="
LINE 7: select result:=MAX(path_history_id)as path INTO result from...
In this function I want to:
execute select with (MAX) and it will return maximum id from a table;
catch that value (it is an integer value);
put that value into last select query where condition.
I cant find a way in postgresql to do this.
CREATE OR REPLACE FUNCTION memcache(IN starting_point_p1 character varying, IN ending_point_p1 character varying)
RETURNS TABLE(path integer, movement_id_out integer, object_id_fk_out integer, path_history_id_fk_out integer, walking_distance_out real, angel_out real, direction_out character varying, time_stamp_out timestamp without time zone, x_coordinate_out real, y_coordinate_out real, z_coordinate_out real) AS
$BODY$
DECLARE result int;
BEGIN
select result:=MAX(path_history_id)as path INTO result from path_history_info where starting_point=starting_point_p1 and ending_point =ending_point_p1 and achieve='1';
return query
select * from movement_info where path_history_id_fk=result;
END;
$BODY$
LANGUAGE plpgsql

Answer 1

Syntax Error
The first query inside your function needs to be changed as follows:
select MAX(path_history_id)as path INTO result
from path_history_info
where starting_point=starting_point_p1
and ending_point =ending_point_p1 and achieve='1';
A single Query
You don't actually need a stored procedure for this. A single query can achieve the same result.
select * from movement_info where path_history_id_fk =
(SELECT MAX(path_history_id) FROM path_history_info
where starting_point=starting_point_p1
and ending_point =ending_point_p1 and achieve='1';