What is the default value for ONDELETE and ONUPDATE for foreign keys in SQL?

Question

I assume that the foreign key reference is set to RESTRICT by default. But is there a standard for this? Is the default value equal for any type of database? Or should these meanings be defined in all statements to be sure?

Answer 1

For postgres, NO ACTION is the default, which for most purposes is similar to RESTRICT, as indicated here .

I would recommend being explicit, especially in DDL, whenever I doubt it (and then some). There are several reasons for this:

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• RDBMS , , ( , )
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Answer 2

, ( ). , , Oracle onupdate