h****r
发帖数: 2056 | 1 say I have two table, A and B
B's every record has a entry in A, how to use trigger to
implement
that when I delete table B, then every record of B's mapping
record
in A also be removed automatically?
Thanks a lot. | s********e
发帖数: 62 | 2 ON DELETE determines how Oracle automatically maintains
referential integrity if
you remove a referenced primary or unique key value. If you
omit this
clause, Oracle does not allow you to delete referenced key
values in the
parent table that have dependent rows in the child table.
CASCADE specifies that Oracle removes dependent foreign key
values.
SET NULL specifies that Oracle converts dependent foreign
key values to NULL.
【在 h****r 的大作中提到】
: say I have two table, A and B
: B's every record has a entry in A, how to use trigger to
: implement
: that when I delete table B, then every record of B's mapping
: record
: in A also be removed automatically?
: Thanks a lot.
| h****r
发帖数: 2056 | 3 thanks a lot. can you give me a simple example to show it.
【在 s********e 的大作中提到】
: ON DELETE determines how Oracle automatically maintains
: referential integrity if
: you remove a referenced primary or unique key value. If you
: omit this
: clause, Oracle does not allow you to delete referenced key
: values in the
: parent table that have dependent rows in the child table.
: CASCADE specifies that Oracle removes dependent foreign key
: values.
: SET NULL specifies that Oracle converts dependent foreign
| s********e
发帖数: 62 | 4 Babylon gave you a good example.
【在 h****r 的大作中提到】
: thanks a lot. can you give me a simple example to show it.
|
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