Question

我有问题。当我第一次创建边时，输出中的记录数就可以了。但是，当我向该类添加另一条记录并再次创建边缘时，我会得到多条记录。这就是我在做的事情。

create class Country extends V
create class Immigrant extends V
create class comesFrom extends E

create property Country.c_id integer
create property Country.c_name String
create property Immigrant.i_id integer
create property Immigrant.i_name String
create property Immigrant.i_country Integer

insert into Country(c_id, c_name) values (1, 'USA')
insert into Country(c_id, c_name) values (2, 'UK')
insert into Country(c_id, c_name) values (3,'PAK')

insert into Immigrant(i_id, i_name,i_country) values (1, 'John',1)
insert into Immigrant(i_id, i_name,i_country) values (2, 'Graham',2)
insert into Immigrant(i_id, i_name,i_country) values (3, 'Ali',3)

create edge comesFrom from (select from Immigrant where i_country = 1) to (select from Country where c_id = 1)
create edge comesFrom from (select from Immigrant where i_country = 2) to (select from Country where c_id = 2)
create edge comesFrom from (select from Immigrant where i_country = 3) to (select from Country where c_id = 3)

select i_id, i_name, out('comesFrom').c_id as c_id, out('comesFrom').c_name as c_name from Immigrant unwind c_id, c_name

我得到如下结果。

Click here to view image of correct records

然后我将另一条记录添加到移民类。

insert into Immigrant(i_id, i_name,i_country) values (4, ‘James',2)

再次创造优势。请注意，新移民属于已经存在的国家。

create edge comesFrom from (select from Immigrant where i_country = 2) to (select from Country where c_id = 2)

我运行如下相同的查询。

select i_id, i_name, out('comesFrom').c_id as c_id, out('comesFrom').c_name as c_name from Immigrant unwind c_id, c_name

现在我得到多条记录如下。

Click here to view image of incorrect records.

我做错了什么。

谢谢！

Answer 1

问题是这个命令：

create edge comesFrom from (select from Immigrant where i_country = 2) 
to (select from Country where c_id = 2)

因为如果你只执行这部分：

select from Immigrant where i_country = 2

你可以看到有两个结果：格雷厄姆和詹姆斯。因此，它将在两个移民（格雷厄姆和詹姆斯）和国家之间创造一个优势。要避免此问题，您可以使用移民的名称创建边缘。但是，我添加了几个附件，以便您可以更好地理解。

问题：http://i.stack.imgur.com/NptOt.png

您的解决方案：http://i.stack.imgur.com/PfU6c.png

我的解决方案：http://i.stack.imgur.com/WEEal.png

此致

OrientDB - 重新应用边缘后显示的多条记录

1 个答案: