如何提高MySQL查询的效率？
以下查询将在0.12秒内执行如何提高MySQL查询的效率？,mysql,Mysql,以下查询将在0.12秒内执行 SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL; SELECT * FROM ( SELECT fav1.user_id, @num := IF(@current_shop_id=shops.shop_id, IF(@current_product_id=products.product_id,@num,@num+1),0) AS row_number, @current_s
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
SELECT * FROM (
SELECT fav1.user_id, @num := IF(@current_shop_id=shops.shop_id, IF(@current_product_id=products.product_id,@num,@num+1),0) AS row_number, @current_shop_id := shops.shop_id AS shop_dummy, @current_product_id := products.product_id AS product_dummy
FROM favorites fav1 INNER JOIN
products ON
fav1.product_id=products.product_id AND
fav1.current=1 AND
fav1.closeted=1 AND
fav1.user_id=30 INNER JOIN
shops ON
shops.shop_id = products.shop_id
GROUP BY fav1.product_id
ORDER BY shops.shop ASC
) AS rowed_results WHERE rowed_results.row_number>=0 AND rowed_results.row_number<(0+5)
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
SELECT * FROM (
SELECT fav1.user_id, @num := IF(@current_shop_id=shops.shop_id, IF(@current_product_id=products.product_id,@num,@num+1),0) AS row_number, @current_shop_id := shops.shop_id AS shop_dummy, @current_product_id := products.product_id AS product_dummy
FROM
#limit results to products favorited by the user whose closet is being shown
favorites fav1 INNER JOIN
products ON
fav1.product_id=products.product_id AND
fav1.current=1 AND
fav1.closeted=1 AND
fav1.user_id=30 INNER JOIN
shops ON
shops.shop_id = products.shop_id
LEFT JOIN
# this LEFT JOIN associates favorites_count table (adds up the scores for all the products in the favorites table)
(
SELECT fav5.product_id AS product_id, SUM(CASE
WHEN fav5.current = 1 AND fav5.closeted = 1 THEN 1
WHEN fav5.current = 1 AND fav5.closeted = 0 THEN -1
ELSE 0
END) AS favorites_count
FROM favorites fav5
GROUP BY fav5.product_id
) AS fav6 ON products.product_id=fav6.product_id
GROUP BY fav1.product_id
ORDER BY shops.shop ASC
) AS rowed_results WHERE rowed_results.row_number>=0 AND rowed_results.row_number<(0+5)
+----+-------------+-------+------+---------------+------+---------+------+-------+----------+---------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------+---------------+------+---------+------+-------+----------+---------------------------------+
| 1 | SIMPLE | fav5 | ALL | NULL | NULL | NULL | NULL | 16377 | 100.00 | Using temporary; Using filesort |
+----+-------------+-------+------+---------------+------+---------+------+-------+----------+---------------------------------+
1 row in set, 1 warning (0.00 sec)
+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message |
+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Note | 1003 | select `my_database`.`fav5`.`product_id` AS `product_id`,sum((case when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 1)) then 1 when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `my_database`.`favorites` `fav5` group by `my_database`.`fav5`.`product_id` |
+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 8846 | 100.00 | Using where |
| 2 | DERIVED | fav1 | ref | user_id,user_id_2,product_id,closeted | user_id_2 | 4 | | 9624 | 100.00 | Using where; Using temporary; Using filesort |
| 2 | DERIVED | products | eq_ref | PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 | PRIMARY | 4 | my_database.fav1.product_id | 1 | 100.00 | |
| 2 | DERIVED | shops | eq_ref | PRIMARY | PRIMARY | 4 | my_database.products.shop_id | 1 | 100.00 | |
| 2 | DERIVED | <derived3> | ALL | NULL | NULL | NULL | NULL | 15764 | 100.00 | |
| 3 | DERIVED | fav5 | ALL | NULL | NULL | NULL | NULL | 16377 | 100.00 | Using temporary; Using filesort |
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
6 rows in set, 1 warning (11.50 sec)
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Note | 1003 | select `rowed_results`.`user_id` AS `user_id`,`rowed_results`.`row_number` AS `row_number`,`rowed_results`.`shop_dummy` AS `shop_dummy`,`rowed_results`.`product_dummy` AS `product_dummy` from (select `my_database`.`fav1`.`user_id` AS `user_id`,(@num:=if(((@current_shop_id) = `my_database`.`shops`.`shop_id`),if(((@current_product_id) = `my_database`.`products`.`product_id`),(@num),((@num) + 1)),0)) AS `row_number`,(@current_shop_id:=`my_database`.`shops`.`shop_id`) AS `shop_dummy`,(@current_product_id:=`my_database`.`products`.`product_id`) AS `product_dummy` from `my_database`.`favorites` `fav1` join `my_database`.`products` join `my_database`.`shops` left join (select `my_database`.`fav5`.`product_id` AS `product_id`,sum((case when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 1)) then 1 when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `my_database`.`favorites` `fav5` group by `my_database`.`fav5`.`product_id`) `fav6` on(((`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`fav6`.`product_id` = `my_database`.`fav1`.`product_id`))) where ((`my_database`.`fav1`.`user_id` = 30) and (`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`my_database`.`shops`.`shop_id` = `my_database`.`products`.`shop_id`) and (`my_database`.`fav1`.`current` = 1) and (`my_database`.`fav1`.`closeted` = 1)) group by `my_database`.`fav1`.`product_id` order by `my_database`.`shops`.`shop`) `rowed_results` where ((`rowed_results`.`row_number` >= 0) and (`rowed_results`.`row_number` < 5)) |
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
|id |选择|类型|类型|可能的|键|键|列|参考|行|过滤|额外|
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
|1 | PRIMARY | | ALL | NULL | NULL | NULL | NULL | 8846 | 100.00 |使用where|
|2 |衍生| fav1 |参考|用户id,用户id | 2,产品id,封闭|用户id | 2 | 4 | 9624 | 100.00 |使用where ;；使用临时设备；使用文件排序|
|2 |衍生|产品| eq | ref |主要，车间| id，车间| id | 2，产品| id，车间| id | 3 |主要| 4 |我的|数据库.fav1.product | id | 1 | 100.00 ||
|2 |派生|店铺| eq | U ref | PRIMARY | PRIMARY | 4 |我的|数据库.产品.店铺| id | 1 | 100.00 ||
|2 |派生| |所有|空|空|空|空| 15764 | 100.00 ||
|3 |派生| fav5 | ALL | NULL | NULL | NULL | NULL | 16377 | 100.00 |使用临时变量；使用文件排序|
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
设置6行，1条警告（11.50秒）
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 8846 | 100.00 | Using where |
| 2 | DERIVED | fav1 | ref | user_id,user_id_2,product_id,closeted | user_id_2 | 4 | | 9624 | 100.00 | Using where; Using temporary; Using filesort |
| 2 | DERIVED | products | eq_ref | PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 | PRIMARY | 4 | my_database.fav1.product_id | 1 | 100.00 | |
| 2 | DERIVED | shops | eq_ref | PRIMARY | PRIMARY | 4 | my_database.products.shop_id | 1 | 100.00 | |
| 2 | DERIVED | <derived3> | ALL | NULL | NULL | NULL | NULL | 15764 | 100.00 | |
| 3 | DERIVED | fav5 | ALL | NULL | NULL | NULL | NULL | 16377 | 100.00 | Using temporary; Using filesort |
+----+-------------+------------+--------+------------------------------------------------+-----------+---------+------------------------------+-------+----------+----------------------------------------------+
6 rows in set, 1 warning (11.50 sec)
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Note | 1003 | select `rowed_results`.`user_id` AS `user_id`,`rowed_results`.`row_number` AS `row_number`,`rowed_results`.`shop_dummy` AS `shop_dummy`,`rowed_results`.`product_dummy` AS `product_dummy` from (select `my_database`.`fav1`.`user_id` AS `user_id`,(@num:=if(((@current_shop_id) = `my_database`.`shops`.`shop_id`),if(((@current_product_id) = `my_database`.`products`.`product_id`),(@num),((@num) + 1)),0)) AS `row_number`,(@current_shop_id:=`my_database`.`shops`.`shop_id`) AS `shop_dummy`,(@current_product_id:=`my_database`.`products`.`product_id`) AS `product_dummy` from `my_database`.`favorites` `fav1` join `my_database`.`products` join `my_database`.`shops` left join (select `my_database`.`fav5`.`product_id` AS `product_id`,sum((case when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 1)) then 1 when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `my_database`.`favorites` `fav5` group by `my_database`.`fav5`.`product_id`) `fav6` on(((`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`fav6`.`product_id` = `my_database`.`fav1`.`product_id`))) where ((`my_database`.`fav1`.`user_id` = 30) and (`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`my_database`.`shops`.`shop_id` = `my_database`.`products`.`shop_id`) and (`my_database`.`fav1`.`current` = 1) and (`my_database`.`fav1`.`closeted` = 1)) group by `my_database`.`fav1`.`product_id` order by `my_database`.`shops`.`shop`) `rowed_results` where ((`rowed_results`.`row_number` >= 0) and (`rowed_results`.`row_number` < 5)) |
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|注| 1003 |选择`排成行的结果'。`用户id`作为`用户id'，`排成行的结果'。`排成行的结果'。`商店虚拟'作为`商店虚拟'，`排成行的结果'。`产品虚拟'作为`产品虚拟'。'((（@current\u-product\u-id）=`my\u-database`.`products`.`products\u-id`），（@num），（@num）+1）），0）作为`row\u-number`，（@current\u-shop\u-id:=`my\u-database`.`shops`.`shop\u-id`）作为`shop\u-dummy`，（@current\u-product\u-id:=`my\u-database`.`products\u-id`作为`我的'数据库'中的'产品'虚拟'。`收藏夹'`fav1`加入`我的'数据库'。`产品'加入`我的'数据库'。`商店'左加入（选择`我的'数据库'。`fav5`.`产品的id`作为`产品的id`，求和（`我的'数据库'`fav5`.`current`=1）和（`我的'我的'数据库'`fav5`.`Closed`=1）的情况下，然后是（`我的'数据库'`fav5`.`current`=1）和（`my_database`.`fav5`.`Closed`=0））然后-（1）否则0结束）作为`my_database`.`favorites``fav5`按`my_database`.`fav5`.`product_id`.`fav6`.`product_id`=`my_database`.`fav1`.`product_id`.`fav6`.`product_id`=`my_database`.`fav1`.`(（`my_database`.`fav1`.`user_id`=30）和（`my_database`.`products`.`product_id`=`my_database`.`fav1`.`product_id`=`30）和（`my_database`.`fav1`.`current`=1）和（`my_database`.`fav1`.`Closed`=1））按“我的”数据库分组。`fav1`.`product\U id`按“我的”数据库分组。`SHOPES`.`SHOPE`）`rowed\U结果`where（`rowed\U结果`.`row\U编号`>=0）和（`rowed\U结果`.`row\U编号`<5））|
+-------+------+-------------------------------------------------------------------------------------------------------------------------------------------------
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Note | 1003 | select `rowed_results`.`user_id` AS `user_id`,`rowed_results`.`row_number` AS `row_number`,`rowed_results`.`shop_dummy` AS `shop_dummy`,`rowed_results`.`product_dummy` AS `product_dummy` from (select `my_database`.`fav1`.`user_id` AS `user_id`,(@num:=if(((@current_shop_id) = `my_database`.`shops`.`shop_id`),if(((@current_product_id) = `my_database`.`products`.`product_id`),(@num),((@num) + 1)),0)) AS `row_number`,(@current_shop_id:=`my_database`.`shops`.`shop_id`) AS `shop_dummy`,(@current_product_id:=`my_database`.`products`.`product_id`) AS `product_dummy` from `my_database`.`favorites` `fav1` join `my_database`.`products` join `my_database`.`shops` left join (select `my_database`.`fav5`.`product_id` AS `product_id`,sum((case when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 1)) then 1 when ((`my_database`.`fav5`.`current` = 1) and (`my_database`.`fav5`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `my_database`.`favorites` `fav5` group by `my_database`.`fav5`.`product_id`) `fav6` on(((`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`fav6`.`product_id` = `my_database`.`fav1`.`product_id`))) where ((`my_database`.`fav1`.`user_id` = 30) and (`my_database`.`products`.`product_id` = `my_database`.`fav1`.`product_id`) and (`my_database`.`shops`.`shop_id` = `my_database`.`products`.`shop_id`) and (`my_database`.`fav1`.`current` = 1) and (`my_database`.`fav1`.`closeted` = 1)) group by `my_database`.`fav1`.`product_id` order by `my_database`.`shops`.`shop`) `rowed_results` where ((`rowed_results`.`row_number` >= 0) and (`rowed_results`.`row_number` < 5)) |
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
CREATE TEMPORARY TABLE fav6 (product_id INT, favorites_count INT, PRIMARY KEY (product_id));
INSERT INTO fav6
SELECT fav5.product_id AS product_id, SUM(CASE
WHEN fav5.current = 1 AND fav5.closeted = 1 THEN 1
WHEN fav5.current = 1 AND fav5.closeted = 0 THEN -1
ELSE 0
END) AS favorites_count
FROM favorites fav5
GROUP BY fav5.product_id;
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
SELECT * FROM (
SELECT fav1.user_id, @num := IF(@current_shop_id=shops.shop_id, IF(@current_product_id=products.product_id,@num,@num+1),0) AS row_number, @current_shop_id := shops.shop_id AS shop_dummy, @current_product_id := products.product_id AS product_dummy
FROM
#limit results to products favorited by the user whose closet is being shown
favorites fav1 INNER JOIN
products ON
fav1.product_id=products.product_id AND
fav1.current=1 AND
fav1.closeted=1 AND
fav1.user_id=30 INNER JOIN
shops ON
shops.shop_id = products.shop_id
LEFT JOIN
fav6 ON products.product_id=fav6.product_id
GROUP BY fav1.product_id
ORDER BY shops.shop ASC
) AS rowed_results WHERE rowed_results.row_number>=0 AND rowed_results.row_number<(0+5)