select update_student(1);

CREATE OR REPLACE FUNCTION public.update_student(id integer)
 RETURNS text AS
$BODY$
declare sql_str_run text; 
BEGIN
/*
--method 1
 select 'update student set remark ='''|| now() ||''' where student.id = '|| $1 into sql_str_run ;
 execute sql_str_run;
 --method 2
 execute 'update student set remark =now() where student.id=$1' using $1;
*/
 --method 3 
 update student set remark =now() where student.id=$1;
 
 return 'update is ok' ;
end
$BODY$
 LANGUAGE plpgsql VOLATILE

a numeric;

select sqla into a from table1 where b = '1' ; --这是sql语句赋值

sql1:= 'select a from table1 where b = ' '1' ' ';
execute sql1 into a; --这是执行存储函数赋值