在 Oracle 中更改 FK 删除规则而不删除和重新创建它？
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Changing a FK delete rule in Oracle without dropping and recreating it?
提问by Greg
Is there a way to change a table FK delete rule in Oracle better than dropping and then adding it again?
有没有比删除然后再次添加更好的方法来更改 Oracle 中的表 FK 删除规则？
I'm currently using:
我目前正在使用：
alter table A
drop constraint my_fk;
alter table A
add constraint my_fk
foreign key (id)
references B(id)
ON DELETE SET NULL;
As you can see, I already have a FK constraint but it had no delete rule on it. I just want to add an ON DELETE SET NULL rule, and that's what I came up with so far, but I'm feeling it should be simpler.
如您所见，我已经有一个 FK 约束，但它没有删除规则。我只想添加一个 ON DELETE SET NULL 规则，这就是我目前想到的，但我觉得它应该更简单。
采纳答案by Michael Pakhantsov
No other way, except drop and re-create constraint. Oracle have syntax ALTER TABLE x MODIFY CONSTRAINT, but it can be used only for change state of constraint.
除了删除并重新创建约束之外别无他法。Oracle 有语法 ALTER TABLE x MODIFY CONSTRAINT，但它只能用于更改约束状态。
http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/statements_3001.htm
http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/statements_3001.htm
