SQL Server 中的可延迟约束

素材狗 2021-01-01 08:20:19 文章分类：数据库问题点击数：次

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Deferrable Constraints in SQL Server(SQL Server 中的可延迟约束)

本文介绍了SQL Server 中的可延迟约束的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

是否有任何版本的 SQL Server 支持可延迟约束 (DC)?

Do any versions of SQL Server support deferrable constraints (DC)?

从 8.0 版本开始，Oracle 支持延迟约束 - 仅在提交语句组时评估的约束，而不是在插入或更新单个表时评估.可延迟约束不同于仅禁用/启用约束，因为约束仍然处于活动状态 - 它们只是稍后评估(当批处理被提交时).

Since about version 8.0, Oracle has supported deferrable constraints - constraints that are only evaluated when you commit a statement group, not when you insert or update individual tables. Deferrable constraints differ from just disabling/enabling constraints, in that the constraints are still active - they are just evaluated later (when the batch is committed).

DC 的好处在于，它们允许对个别非法的更新进行评估，从而累积导致有效的最终状态.一个例子是在两行之间的表中创建循环引用，其中每行都需要一个值.没有单独的插入语句会通过约束 - 但组可以.

The benefit of DC is that they allow updates that individually would be illegal to be evaluated that cummulatively result in a valid end state. An example is creating circular references in a table between two rows where each row requires a value to exist. No individual insert statement would pass the constraint - but the group can.

为了阐明我的目标，我希望将 C# 中的 ORM 实现移植到 SQLServer - 不幸的是，该实现依赖于 Oracle DC 来避免在行之间计算插入/更新/删除订单.

To clarify my goal, I am looking to port an ORM implementation in C# to SQLServer - unfortunately the implementation relies on Oracle DC to avoid computing insert/update/delete orders amongst rows.