任务：
考虑一个关系 (,,,,,,) 及其 FD 集 = { → , → , → , → , → , → }。如果它不在 BCNF 中，则将其分解为 BCNF 关系的集合。确保您的分解是无损连接。
解释
嗨，我正在做我的数据库作业（关系设计章节）。我想我已经根据课堂示例掌握了基本过程。然而，这里棘手的部分是我们有一个与其他人没有关系的属性“H”，这让我很困惑。我应该如何处理？
尝试回答
• We start from a schema: ABCDEGH, since H has no relations with any attribute, we decompose it into tables: H and ABCDEG
• The FDs for ABCDEG remains the same, therefore key is E.
• The FD D →AG violates BCNF (FD with non-key on LHS).
• To fix, we need to decompose into tables: ADG and BCDE
• FDs for ADG are { D → AG }, therefore key is D, therefore BCNF.
• FDs for BCDE are { B → CD, E → D, BC → DE, E → B, CD → BE }
• Key for BCDE is also E, and FD B → CD violates BCNF (FD with non-key on LHS).
• To fix, we need to decompose into tables: BCD and BE
• FDs for BCD are { B → CD } therefore key is B, therefore BCNF.
• FDs for BE are { E → B } therefore key is E, therefore BCNF.
• Final schema: H, ADG, BCD, BE
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