mysql में, क्या आप एक उपनाम को एक दूसरे से विभाजित कर सकते हैं?

Question

मैं एक बहु-तालिका क्वेरी, इस (सरलीकृत संस्करण) के लिए इसी तरह

SELECT columns, count(table2.rev_id) As rev_count, sum(table2.rev_rating) As sum_rev_rating 
FROM table1 
LEFT JOIN table2 
ON table1.dom_id = table2.rev_domain_from 
WHERE dom_lastreview != 0 AND rev_status = 1 
GROUP BY dom_url 
ORDER BY sum_rev_rating/rev_count DESC 

समस्या ORDER BY खंड में है। यह एक mysql त्रुटि को दिखाने के लिए कारण बनता है, जो इस प्रकार है:

संदर्भ 'sum_ rev_ रेटिंग' समर्थित नहीं (समूह समारोह के संदर्भ में)

Answer 1

आप उपनाम के साथ गणना करने के लिए सक्षम नहीं हैं। ऐसा करने का एक तरीका बस इसके द्वारा एक और उपनाम और आदेश बनाना होगा।

SELECT columns, count(table2.rev_id) As rev_count, sum(table2.rev_rating) As sum_rev_rating, sum(table2.rev_rating)/count(table2.rev_id) as avg_rev_rating 
FROM table1 
LEFT JOIN table2 
ON table1.dom_id = table2.rev_domain_from 
WHERE dom_lastreview != 0 AND rev_status = 1 
GROUP BY dom_url 
ORDER BY avg_rev_rating DESC 

Answer 2

मेरी mysql जंग लगी है, आप कोशिश कर सकते हैं

SELECT columns, count(table2.rev_id) As rev_count, 
    sum(table2.rev_rating) As sum_rev_rating, 
    sum(table2.rev_rating)/count(table2.rev_id) as rev_ratio 
FROM table1 
    LEFT JOIN table2ON table1.dom_id = table2.rev_domain_from 
WHERE dom_lastreview != 0 
AND rev_status = 1 
GROUP BY dom_url 
ORDER BY rev_Ratio DESC 

या

SELECT * from (
    SELECT columns, count(table2.rev_id) As rev_count, 
     sum(table2.rev_rating) As sum_rev_rating 
    FROM table1 
     LEFT JOIN table2ON table1.dom_id = table2.rev_domain_from 
    WHERE dom_lastreview != 0 
    AND rev_status = 1 
    GROUP BY dom_url 
) X 
ORDER BY X.sum_rev_rating/X.rev_count DESC 

या

SELECT * from (
    SELECT columns, count(table2.rev_id) As rev_count, 
     sum(table2.rev_rating) As sum_rev_rating, 
     sum(table2.rev_rating)/count(table2.rev_id) as rev_ratio 
    FROM table1 
     LEFT JOIN table2ON table1.dom_id = table2.rev_domain_from 
    WHERE dom_lastreview != 0 
    AND rev_status = 1 
    GROUP BY dom_url 
) X 
ORDER BY rev_Ratio DESC