Question

我有一些带有外键的表。表的结构并不重要。例如，表A是顶层表。表B和C在表A上具有外键，而表D，E和F和G在表B和C上具有外键。问题是：有没有办法从表A中克隆行之一使用SQL进行所有操作（行B-G）？

Answer 1

您没有提供结构或数据，因此您必须使用我的示例。基本思路是，随着从父级到子级的进行，只需要在相应的PK列中选择适当的FK列。

-- create base tables
create table a (a_id integer, a_col1 text, constraint a_pk primary key (a_id)); 
create table b (b_id integer, a_id integer, b_col1 text
               , constraint b_pk primary key (b_id)
               , constraint b_fk_a foreign key (a_id)
                 references a(a_id)
               );
create table g (g_id integer, b_id integer, g_col1 text
               , constraint g_pk primary key (g_id)
               , constraint g_fk_b foreign key (b_id)
                 references b(b_id)
               );       

-------------------------------------------------------------------------------------------------------
-- populate
insert into a (a_id,a_col1)      values (11,'ta1'), (12,'ta2');
insert into b (b_id,a_id,b_col1) values (21,11,'tb1'), (22,11,'tb2'), (23,12,'tb3'), (24,12,'tb4');  
insert into g (g_id,b_id,g_col1) values (71,21,'tg1'), (72,21,'tg2'), (73,22,'tg3'), (74,22,'tg4')
                                      , (75,23,'tg5'), (76,23,'tg6'), (77,24,'tg7'), (78,24,'tg8');  
-------------------------------------------------------------------------------------------------------
-- Soution: clone a_id 12
create table a_clone as 
       select * 
         from a 
        where a_id = 12;

create table b_clone as 
       select * 
         from b 
      where a_id = 12; 

create table g_clone as 
       select * 
         from g
        where b_id in
              (select b_id
                 from b 
                where a_id = 12
              );
-- done

Sticky Bit的“想到”建议是可行的，但并非一帆风顺。我相信上面的内容很简单。

如何将行从一个表复制到另一个具有依赖关系的表？

1 个答案: