If the following functional dependencies holds on a selection R : A → B, A → C, BC → D, C → F, B → E, then which of the following dependency does not hold on R ?
यदि एक रिलेशन R पर निम्न कार्यात्मक निर्भरताएँ मौजूद हैं : A → B, A → C, BC → D, C → F, B → E, तब निम्न में से कौन-सी कार्यात्मक निर्भरता R पर मौजूद नहीं है ?
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Correct answer: D. BD → EF
Explanation
A → B, C gives A → D (via BC) and A → E, F. BC → D, E, F holds too. But BD⁺ = {B, D, E}; F needs C, so BD → EF does not hold.
A से B, C, D, E, F सब मिलते हैं और BC → DEF भी सही है। पर BD⁺ = {B, D, E}; F के लिए C चाहिए, अतः BD → EF लागू नहीं।
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