| 摘要 |
A method, in a data processing system, of imposing constraints on data files which are changed by update statements, includes the steps of: a) identifying a particular object of the update Ox and a particular attribute being updated; b) finding an applicable constraint based on the particular attribute being updated; c) converting the particular update object Ox to at least one other object which is in the applicable constraint and is different than the update object Ox; and, d) generating an error message, if after the update, the applicable constraint is not satisfied by any object from the converting step.
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