postgresql - How To Do Percent/Total in SQL? -

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मेरे पास विशिष्ट ठेकेदार / आदेश तालिकाएँ हैं और मैं कुल प्रतिशत प्रदर्शित करना चाहता हूं बिक्री के लिए एक विशेष ग्राहक जिम्मेदार है मैं इस तरह से सिस्टम में कुल आदेशों की संख्या प्राप्त कर सकता हूं: 

  ऑर्डर से SELECT COUNT (order_id)

और मैं कुल संख्या प्राप्त कर सकता हूँ जैसे ग्राहकों द्वारा किए गए आदेशों का: 

  SELECT COUNT (order_id) आदेशों से WHERE cust_id = 541

मैं इन्हें एक ही क्वेरी में कैसे जोड़ सकता हूं कि किसी विशेष ग्राहक के लिए बिक्री का प्रतिशत देता है? धन्यवाद!

माइस् SQL: 

  SELECT ROUND (100.0 * (SUM) (IF (cust_id = 541, 1, 0)) / COUNT (आदेश_आईडी)), 1) आदेश से प्रतिशत_टाल के रूप में;    संपादन   
 मुझे लगता है कि यह मदद करता है अगर मुझे  पोस्टग्रेज़  टैग पर गौर करना होता। मैंने सोचा कि यह एक MySQL प्रश्न था।  
 PostgreSQL:  
  का चयन करें राउंड (100.0 * (SUM (केस जब cust_id = 541 THEN 1 ELSE 0 END) / COUNT (order_id )), 1) के रूप में आदेश से प्रतिशत%;  
 
 पीएस मेरा PostgreSQL जंग खाए है, इसलिए यदि MySQL क्वेरी PostgreSQL पर काम करता है तो मैं जानना चाहूंगा:) 
 
  संपादित करें 2  
 
 मैं पर्याप्त रूप से तनाव नहीं कर सकता नीचे गिनती (*) सुझाव से सावधान रहना आप आमतौर पर इसे PostgreSQL से बचाना चाहते हैं।

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