Referential Integrity (324)

Because Oracle does not use read locks in either read-consistent or serializable
transactions, data read by one transaction can be overwritten by another. Transactions
that perform database consistency checks at the application level cannot assume that
the data they read will remain unchanged during the execution of the transaction even
though such changes are not visible to the transaction. Database inconsistencies can
result unless such application-level consistency checks are coded with this in mind,
even when using serializable transactions.

引用完整性
1. 無論在已提交讀取隔離模式還是序列化隔離模式中，Oracle 都不會使用讀取鎖

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