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Article #1063Re: ������ڷ�ʽ�жϵ����⡫
From: �շ�����&���²���
Date: Thu, 17 Apr 2008 04:32
Date: Thu, 17 Apr 2008 04:32
23 lines
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1480 bytes
1.AB������ D�������Dz������� ���Բ����2NF
2.D�Ƿ������� AB������ʱ AB->C->D ��������
3.AB������ C�������Dz�������
�� �� bingomickey (����Ȫ��) �Ĵ������ᵽ: ��
: R(ABCD) 1NF
: F={B->D,AB->C}
: R(ABCDE) 2NF
: F={AB->CE,E->AB,C->D}
: R(ABC) 1NF
: F={A->C}
: ��Щ������ô�жϵģ�лл�ˡ�
--
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X-Google-Thread: 101948,2265977d2a7d09f2,start X-Google-Attributes: gid101948,domainid0,public,usenet X-Google-Language: Chinese,GB Path: arc1-ca.pugleaf.net!g2news1.google.com!news2.google.com!news.glorb.com!news.neu.edu.cn!news.shec6.edu.cn!SJTU From: bupabupa.bbs@bbs.sjtu.edu.cn (�շ�����&���²���) Newsgroups: cn.bbs.comp.database Subject: Re: ������ڷ�ʽ�жϵ����⡫ Date: 17 Apr 2008 04:32:03 GMT Organization: ��ˮ˼Դ Message-ID: <4ZUY1A$bKb@bbs.sjtu.edu.cn> Mime-Version: 1.0 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: 8bit X-Filename: database/M.1208406586.A