如何在 Oracle APEX 中的 Oracle 数据库建模器中重新创建弧关系？

Question

I'm not sure how to write out a foreign key constraint in Oracle APEX that will represent an arc relationship in the Oracle Database Modeler.

Answer 1

You can let the datamodeler generate the relational model and the DDL code. Then, open the SQL script editor in APEX, paste in the DDL code, give the script a name, and execute it - see screen shots below.

(example) ERD

Relational model (generated)

DDL code (generated)

APEX script editor (notice the CHECK constraint enforcing the "arc")

Script executed

You may have to tweak the script a bit (if there are error messages).

Then, you should do some testing, so that you see that the "arc" actually works eg

Testing

-- these 3 INSERTs must fail
-- {1} event without a "venue id"
insert into event ( 
  id, eventdate, private_home_id, public_space_id 
) values (
  1, sysdate, null, null
) ;
-- ORA-02290: check constraint (...ARC_1) violated

-- {2} private home does not exist
insert into event ( 
  id, eventdate, private_home_id, public_space_id 
) values (
  1, sysdate, 1000, null
) ;
-- ORA-02291: integrity constraint (...EVENT_PRIVATE_HOME_FK) violated - parent
key not found

-- {3} public space does not exist
insert into event ( 
  id, eventdate, private_home_id, public_space_id 
) values (
  1, sysdate, null, 2000
) ;
-- ORA-02291: integrity constraint (...EVENT_PUBLIC_SPACE_FK) violated - parent
key not found

INSERT some data into the PRIVATE_HOME and PUBLIC_SPACE tables

-- add a PRIVATE_HOME and a PUBLIC_SPACE
insert into private_home( id, vname ) values ( 1000, 'The Manor' ) ;
insert into public_space( id, vname ) values ( 2000, 'Royal Albert Hall' ) ;


-- add 2 events
insert into event ( 
  id, eventdate, private_home_id, public_space_id 
) values (
  1, sysdate, 1000, null
) ;

insert into event ( 
  id, eventdate, private_home_id, public_space_id 
) values (
  2, sysdate, null, 2000
) ;

select * from event ;
SQL> select * from event ;

        ID EVENTDATE PRIVATE_HOME_ID PUBLIC_SPACE_ID
---------- --------- --------------- ---------------
         1 06-MAY-20            1000                
         2 06-MAY-20                            2000