sql - Should I use Primary key here? -

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एक उदाहरण के रूप में, मेरे पास 3 टेबल हैं: 

  स्कूल: ID int, नाम Varchar छात्र: ID int, नाम varchar StudentInSchool: StudentID int, SchoolID int

अब सवाल यह है कि मुझे एक कॉलम ID int रखना चाहिए StudentInSchool तालिका में प्राथमिक कुंजी ? यदि हां, तो क्यों?

क्या यह अनुक्रमण करने में सहायक होगा?

कोई भी मदद की सराहना की।

व्यक्तिगत तौर पर, मैं समग्र पीके ( StudentID और SchoolID ) इस तरह तैयार करता हूं। यह विशिष्टता भी सुनिश्चित करता है।

अगर, विशिष्टता की आवश्यकता नहीं है, आपको प्रत्येक पंक्ति को विशिष्ट रूप से पहचानने के लिए एक आईडी कॉलम जोड़ना होगा।

आम तौर पर, एक अलग आईडी कॉलम के अलावा ज्यादा मदद नहीं मिलेगी: बहुत कम प्रश्न (यदि कोई हो) वास्तव में इस कॉलम का उपयोग करेगा। प्रदर्शन के लिए, आप प्रत्येक कॉलम के लिए अलग-अलग अनुक्रमणिका बना सकते हैं और आप बस ठीक हो जाएंगे।


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