以更高性能短接mysql查詢

如何縮短此查詢？以更高性能短接mysql查詢

SET sql_mode = ''; 
SELECT t1.`id_number`,t1.`parents_id_number`,t1.`student_first_name`, 
    SUM(t1.`degree_value`) AS `values`, 
    (SELECT `user_key` 
     FROM data_users.account_info t2 
     WHERE t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
     LIMIT 1) AS `user_key`, 
    (SELECT `first_name` 
     FROM data_users.account_info t2 
     WHERE t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
     LIMIT 1) AS `first_name`, 
    (SELECT `last_name` 
     FROM data_users.account_info t2 
     WHERE t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
     LIMIT 1) AS `last_name`, 
    (SELECT `about_me` 
     FROM data_users.account_info t2 
     WHERE t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
     LIMIT 1) AS `about_me` 
FROM `1479213957519` t1  
WHERE t1.year_half = '1' 
GROUP BY t1.`perfix` 
ORDER BY `Values` DESC 
LIMIT 6

來源

2017-01-01 Saef Myth

見http://meta.stackoverflow.com/questions/333952/why-should-i-provide-an-mcve-for-what-seems-to-me-to-be-a-very -simple-sql-query – Strawberry

如果你有一個名爲1479213957519的表，那麼可能是某個地方出現了嚴重錯誤 – Strawberry

那是自動生成後數據表 –

使用連接而不是相關子查詢。

SELECT t1.`id_number`,t1.`parents_id_number`,t1.`student_first_name`, 
     SUM(t1.`degree_value`) AS `values`, 
     t2.user_key, t2.first_name, t2.last_name, t2.about_me 
FROM `1479213957519` t1 
JOIN (SELECT * 
     FROM data_users.account_info 
     GROUP BY id_number, parents_id_number) t2 
    ON t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
WHERE t1.year_half = '1' 
GROUP BY t1.`perfix` 
ORDER BY `Values` DESC 
LIMIT 6

如果id_number和parents_id_number唯一標識account_info一排，你不需要子查詢，你可以只用表本身加入。

SELECT t1.`id_number`,t1.`parents_id_number`,t1.`student_first_name`, 
     SUM(t1.`degree_value`) AS `values`, 
     t2.user_key, t2.first_name, t2.last_name, t2.about_me 
FROM `1479213957519` t1 
JOIN data_users.account_info t2 
    ON t1.id_number = t2.id_number AND t1.parents_id_number = t2.parents_id_number 
WHERE t1.year_half = '1' 
GROUP BY t1.`perfix` 
ORDER BY `Values` DESC 
LIMIT 6

來源

2017-01-01 09:27:22 Barmar

perfcto man ,,,第二個查詢花了0.0014秒，第一個0.263，而我的花了0.334 ,,我需要學習更多的sql ,,,謝謝花花公子 –

以更高性能短接mysql查詢

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