PostgreSQL – 正确更改表行的ID

create table referenced (id integer primary key);
create table referencer (a integer references referenced (id));

引用的表引用器引用表：

=> d referencer
  Table "public.referencer"
 Column |  Type   | Modifiers 
--------+---------+-----------
 a      | integer | 
Foreign-key constraints:
    "referencer_a_fkey" FOREIGN KEY (a) REFERENCES referenced(id)

然后在两者中插入一个值：

insert into referenced values (1);
insert into referencer values (1);

select *
from
    referenced rd
    inner join
    referencer rr on rd.id = rr.a
;
 id | a 
----+---
  1 | 1

现在您要更改对更新级联的引用：

alter table referencer
    drop constraint referencer_a_fkey,add foreign key (a) references referenced (id) on update cascade;

并更新它：

update referenced set id = 2;

select *
from
    referenced rd
    inner join
    referencer rr on rd.id = rr.a
;
 id | a 
----+---
  2 | 2

现在,如果已更新的ID已存在,则在引用的表主键中将出现另一个问题.但这会产生另一个问题.

UPDATE

这很危险,所以首先备份数据库.必须以超级用户身份完成：

update pg_constraint
set confupdtype = 'c'
where conname in (
    select
        c.conname
    from
        pg_constraint c
        inner join
        pg_class referenced on referenced.oid = c.confrelid
    where
        referenced.relname = 'referenced'
        and
        c.contype = 'f'
);

它会将引用表上的所有外键约束更改为更新级联