2017-06-11 125 views
0

以下排序依據是MySQL查詢:混淆在MySQL查詢

SELECT * FROM `is_product_info` ORDER BY (select distinct product_id from is_product_images where is_product_images.product_id = is_product_info.id) asc 

我沒有得到如何通過使用子查詢在這裏工作的順序。

我遇到過這樣的查詢,在wordpress插件中有子查詢。這對我來說是新的,所以我問是否有人知道這一點。下面是這樣的例子:

SELECT wp22_posts.* 
    FROM wp22_posts 
    LEFT 
    JOIN wp22_term_relationships 
    ON wp22_posts.ID = wp22_term_relationships.object_id 
WHERE 1=1 
    AND wp22_posts.ID IN(260,412,413,414,415,469,474,483 
         ,485,487,488,515,516,563,568‌​,569 
         ,584,592,593,596‌​,599,601,604,610 
         ,612‌​,672,675,678,681,690‌​,860,861,862,863) 
GROUP 
    BY wp22_posts.ID 
ORDER 
    BY (SELECT distinct meta_value from wp22_postmeta where'meta_key' LIKE 'price') ASC 
LIMIT 0, 10 

有沒有人描述這個查詢?

+0

這是因爲它是亂碼 – Strawberry

+0

我在wordpress插件中遇到了按子查詢排序的查詢。這對我來說是新的,所以我問是否有人知道這一點。 下面是這樣的例子: SELECT wp22_posts * FROM wp22_posts LEFT JOIN wp22_term_relationships ON(wp22_posts.ID = wp22_term_relationships.object_id)其中1 = 1 AND(wp22_posts.ID在(260,412,413,414,415,469,474,483,485,487,488,515,516,563,568,569,584,592,593,596,599,601,604,610,612,672,675,678,681,690,860,861,862,863))GROUP BY wp22_posts.ID ORDER BY(從wp22_postmeta中選擇不同的meta_value where'meta_key'LIKE'price')ASC LIMIT 0,10 –

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但是,示例WordPress查詢非常差,並且由不太瞭解他們在做什麼的人構建 – Strawberry

回答

0

要回答你的問題,ORDER BY子句根本不做任何事情(除了可能停止查詢的工作)。