Question

如何将这个大查询转换为存储过程，我应该怎么做？有什么好处？

SELECT * 
FROM user_items
LEFT JOIN items ON (items.item_id = user_items.item_id) 
INNER JOIN item_categories ON (item_categories.item_id = items.item_id)
INNER JOIN item_subcategories ON (item_subcategories.item_id = items.item_id)
INNER JOIN brands ON (brands.brand_id = items.item_brand)
INNER JOIN item_photos ON (item_photos.item_id = items.item_id)

INNER JOIN place_items ON (place_items.item_id = items.item_id)
INNER JOIN places ON (places.place_id = place_items.place_id)

WHERE user_items.user_id = :user_id

brands

我只需要brand_name

places

我只需要place_name

我现在正在做的方式，我从brands和places得到所有列，所以我的一个朋友告诉我，我应该考虑使用存储过程

Answer 1

如果您只想要品牌和商品表中的列，则可以执行以下操作

"SELECT   brands.brand_name,places.place_name,
          user_items.*,items.*,item_categories .*,
          item_subcategories.*,item_photos.*,place_items.*
 FROM user_items
          LEFT JOIN items ON (items.item_id = user_items.item_id) 
          INNER JOIN item_categories ON (item_categories.item_id = items.item_id)
          INNER JOIN item_subcategories ON (item_subcategories.item_id = items.item_id)
          INNER JOIN brands ON (brands.brand_id = items.item_brand)
          INNER JOIN item_photos ON (item_photos.item_id = items.item_id)

          INNER JOIN place_items ON (place_items.item_id = items.item_id)
          INNER JOIN places ON (places.place_id = place_items.place_id)

          WHERE user_items.user_id = :user_id"

使用存储过程是重用一组SQL语句。存储过程的性能与它包含的SQL语句一样好。

更好的方法是提高代码的可读性，可以使用 ALIASES 来表名。

When to use SQL Table Alias

Answer 2

根据我的经验，存储过程比它们值得更加麻烦，缺乏灵活性，因此比内联SQL更难维护，驻留在版本控制之外，并且如果有任何性能优势则无法提供很多。在这种情况下，存储的例程似乎没有必要或有益，因为您的查询不需要高级功能，例如光标。有关优缺点的另一个讨论，请参阅this post。

Answer 3

    DELIMITER $$
    DROP PROCEDURE IF EXISTS `ABC` $$
    CREATE PROCEDURE `ABC`(IN UID LONG)
    READS SQL DATA
    BEGIN
    SELECT * 
    FROM user_items
    LEFT JOIN items ON (items.item_id = user_items.item_id) 
    INNER JOIN item_categories ON (item_categories.item_id = items.item_id)
    INNER JOIN item_subcategories ON (item_subcategories.item_id = items.item_id)
    INNER JOIN brands ON (brands.brand_id = items.item_brand)
    INNER JOIN item_photos ON (item_photos.item_id = items.item_id)
    INNER JOIN place_items ON (place_items.item_id = items.item_id)
    INNER JOIN places ON (places.place_id = place_items.place_id)
    WHERE user_items.user_id = UID
    END $$
    DELIMITER ;



you can do like this and execute this and can call then :-

CALL ABC(1234);

where 1234 is user_id of user. Thank you

如何将这个大查询转换为存储过程

3 个答案: