MySQL 查询在 phpMyAdmin 中运行正常，但在 PHP 中挂起

Question

我有一个相当简单的查询，当我在 phpMyAdmin 中测试它时运行正常：

   SELECT   
        c.customers_id,
        c.customers_cid,
        c.customers_gender,
        c.customers_firstname,
        c.customers_lastname,
        c.customers_email_address,
        c.customers_telephone,
        c.customers_date_added,
        ab.entry_company,
        ab.entry_street_address,
        ab.entry_postcode, 
        ab.entry_city,
        COUNT(o.customers_id) AS orders_number,
        SUM(ot.value) AS totalvalue, 
        mb.bonus_points
   FROM     
        orders AS o,
        orders_total AS ot,
        customers AS c, 
        address_book AS ab, 
        module_bonus AS mb
   WHERE 
        c.customers_id = o.customers_id 
        AND c.customers_default_address_id = ab.address_book_id 
        AND c.customers_id = mb.customers_id    
        AND o.orders_id = ot.orders_id 
        AND ot.class = 'ot_subtotal'    
 **  AND c.customers_gender  = 'm' AND c.customers_lastname LIKE 'Famlex'
    GROUP BY o.customers_id

标有**的行会根据进行查询的应用程序的过滤设置而变化。

现在，当我在 phpMyAdmin 中对此进行测试时，查询需要几秒钟才能运行（这很好，因为有数千个条目，而且据我所知，使用 COUNT 和 SUM 索引时没有帮助) 并且结果很完美，但是当我在 PHP 中运行完全相同的查询时（在运行前回显），MySQL 线程将内核加载到 100% 并且在我杀死它之前不会停止。

如果我去掉多余的东西来计算 COUNT 和 SUM，则查询完成，但结果对我来说毫无用处。

解释：

1   SIMPLE  mb  ALL     NULL                        NULL        NULL        NULL                                48713       Using temporary; Using filesort
1   SIMPLE  ot  ALL     idx_orders_total_orders_id  NULL        NULL        NULL                                811725      Using where
1   SIMPLE  o   eq_ref  PRIMARY                     PRIMARY     4           db.ot.orders_id                     1           Using where
1   SIMPLE  c   eq_ref  PRIMARY                     PRIMARY     4           db.o.customers_id                   1           Using where
1   SIMPLE  ab  eq_ref  PRIMARY                     PRIMARY     4           db.c.customers_default_address_id   1

应用索引和使用连接后的解释：

1   SIMPLE  c   ref     PRIMARY,search_str_idx              search_str_idx          98      const                                   1       Using where; Using temporary; Using filesort
1   SIMPLE  mb  ALL     NULL                                NULL                    NULL    NULL                                    48713   Using where
1   SIMPLE  ab  eq_ref  PRIMARY                             PRIMARY                 4       db.c.customers_default_address_id       1    
1   SIMPLE  ot  ref     idx_orders_total_orders_id,class    class                   98      const                                   157004  Using where
1   SIMPLE  o   eq_ref  PRIMARY                             PRIMARY                 4       db.ot.orders_id                         1       Using where

Answer 1

使用显式连接而不是隐式连接

SELECT  
c.customers_id,
c.customers_cid,
c.customers_gender,
c.customers_firstname,
c.customers_lastname,
c.customers_email_address,
c.customers_telephone,
c.customers_date_added,
ab.entry_company,
ab.entry_street_address,
ab.entry_postcode, 
ab.entry_city,
COUNT(o.customers_id) AS orders_number,
SUM(ot.value) AS totalvalue, 
mb.bonus_points
FROM    
orders o 
join orders_total ot on o.orders_id = ot.orders_id 
join customers c on c.customers_id = o.customers_id 
join address_book ab on c.customers_default_address_id = ab.address_book_id 
join module_bonus mb on c.customers_id = mb.customers_id 
where
ot.class = 'ot_subtotal'
c.customers_gender  = 'm' 
AND c.customers_lastname = 'Famlex'
GROUP BY o.customers_id

假设所有连接键也是这些表的主键，即：

o.orders_id, c.customers_id, ab.address_book_id 

如果尚未添加以下索引，则需要添加它们

alter table  orders add index customers_id_idx(customers_id);
alter table module_bonus add index customers_id_idx(customers_id);
alter table orders_total add index orders_id_idx(orders_id);
alter table orders_total add index orders_class_idx(class);
alter table customers add index search_str_idx(customers_gender,customers_lastname);

确保在应用索引之前备份表。

Answer 2

您能否分享您的记录的 SQL 转储以便我查看？

phpMyAdmin 自动将限制子句添加到 select 查询中，这就是为什么我认为您会觉得 phpMyAdmin 查询运行良好但不是通过您的 PHP 脚本运行的原因。 尝试在运行前在 phpMyAdmin 中的查询中添加显式限制子句，例如 limit 0, 1000，看看这是否会使 phpMyAdmin 的性能变慢。