postgres procedure giving ERROR: invalid input syntax for type timestamp: "select CURRENT_TIMESTAMP - INTERVAL '7 day'"

Question

我已经创建了 postgres 过程，我不会在这里写整个过程，只写下面给出错误的部分，

create or replace procedure xyz() as $$
declare
  v_time timestamp without time zone;
  v_retain_days int;
Begin
  select retain_days from abc into v_retain_days;
  v_time := cast('select CURRENT_TIMESTAMP - INTERVAL ''' || v_retain_days || ' day''' as timestamp) ;
END;

调用这个程序，报错如下：

ERROR: invalid input syntax for type timestamp: "select CURRENT_TIMESTAMP - INTERVAL '7 day'"

有人可以帮忙吗？

Answer 1

无需 SELECT、动态 SQL、转换或字符串连接：

v_time := CURRENT_TIMESTAMP - INTERVAL '1 day' * v_retain_days;

或者：

v_time := CURRENT_TIMESTAMP - make_interval(days => v_retain_days);

postgres procedure giving ERROR: invalid input syntax for type timestamp: "select CURRENT_TIMESTAMP - INTERVAL '7 day'"

postgres procedure giving ERROR: invalid input syntax for type timestamp: "select CURRENT_TIMESTAMP - INTERVAL '7 day'"

postgresql

procedure