Question

我具有以下数据库结构：

table a (
    id     bigint primary key,
    del    timestamp
);
table b (
    id     bigint primary key,
    a_id   bigint references a(id) on delete cascade,
    del    timestamp
);

从表a删除记录时，我想在当前时间设置del标志，并将表b中的相应标志设置为大写（但实际上不从数据库中删除记录）。

为此，我编写了一个触发器：

create or replace function a_delete_trigger()
    returns trigger as
$$
begin
    update a
    set del = now()
    where id = old.id; -- mark row

    return null; -- return null, so that the record is not removed from database
end;
$$
language plpgsql;
create trigger a_delete
    before delete
    on a
    for each row
execute procedure a_delete_trigger();

以及表b的触发器：

create or replace function b_delete_trigger()
    returns trigger as
$$
begin
    update b
    set del = now()
    where id = old.id;

    return null;
end;
$$
language plpgsql;
create trigger b_delete
    before delete
    on b
    for each row
execute procedure b_delete_trigger();

当我从表a（delete from a where id = ?）中删除一条记录时，该记录被标记为已删除（标志del包含时间戳记），但是表{{1}中的适当记录}没有标记（我猜想，级联删除不起作用，因为我从触发器b返回null）

我该如何做，当我从表a_delete_trigger中删除一条记录时，该记录标记为已删除，而a中的相应记录也将标记为已删除？

Answer 1

将删除项b添加到a_delete_trigger。

create or replace function a_delete_trigger()
    returns trigger as
$$
begin
    update a
    set del = now()
    where id = old.id; -- mark row

    delete from b where a_id = a.id;

    return null; -- return null, so that the record is not removed from database
end;
$$
language plpgsql;
create trigger a_delete
    before delete
    on a
    for each row
execute procedure a_delete_trigger();

Postgres级联删除与触发器

1 个答案: