需要帮助优化 MySQL 具有少量连接的查询

Question

你好，我有以下 sql 查询，它有效，但有点慢

SELECT 
    ep . *,
    t_u.sUsername AS sLockedBy,
    epi.sName,
    em.sName AS sManufacturerName,
    SUM(IF(eop.dInProduction IS NULL
            AND eop.dFromProduction IS NULL
            AND eop.dShipped IS NULL
            AND eop.nIsCancelled = 0
            AND eos.sStatusCode NOT IN ('Canceled' , 'Finished', 'Complete'),
        1,
        0)) AS nProductOrdered,
    SUM(IF(eop.dInProduction IS NOT NULL
            AND eop.dFromProduction IS NULL
            AND eop.dShipped IS NULL
            AND eop.nIsCancelled = 0
            AND eos.sStatusCode NOT IN ('Canceled' , 'Finished', 'Complete'),
        1,
        0)) AS nProductInProduction,
    SUM(IF(eop.dInProduction IS NOT NULL
            AND eop.dFromProduction IS NOT NULL
            AND eop.dShipped IS NULL
            AND eop.nIsCancelled = 0
            AND eos.sStatusCode NOT IN ('Canceled' , 'Finished', 'Complete'),
        1,
        0)) AS nProductFromProduction,
    SUM(IF(eop.dInProduction IS NULL
            AND eop.dFromProduction IS NULL
            AND eop.dShipped IS NULL
            AND eop.nIsCancelled = 0
            AND eos.sStatusCode NOT IN ('Canceled' , 'Finished', 'Complete'),
        1,
        0)) + ep.nInStock AS nStockCheck
FROM
    eshop3_products AS ep
        LEFT JOIN
    users AS t_u ON ep.nUserLockID = t_u.nUID
        AND t_u.nDeleted = 0
        INNER JOIN
    eshop3_products_i18n AS epi ON ep.nUID = epi.nProductID
        AND epi.nLangID = 1
        AND epi.nDeleted = 0
        LEFT JOIN
    eshop3_manufacturers AS em ON ep.nManufacturerID = em.nUID
        AND em.nDeleted = 0
        LEFT JOIN
    eshop3_order_products AS eop ON ep.nUID = eop.nProductID
        LEFT JOIN
    eshop3_orders AS eo ON eop.nOrderID = eo.nUID
        LEFT JOIN
    eshop3_order_statuses AS eos ON eo.nUID = eos.nOrderID
        AND eos.nUID = (SELECT 
            nUID
        FROM
            eshop3_order_statuses as eos
        WHERE
            eo.nUID = eos.nOrderID
        ORDER BY eos.nUID DESC
        LIMIT 1)
WHERE
    (ep.nDeleted = 0)
GROUP BY ep.nUID
ORDER BY ep.sStoreCode ASC

产品 Table 共有 462 行，

订单状态 Tables 共有 17 154 行

查询的执行时间是 1.5 秒，我认为它很慢。

我在ON子句中使用INNER SELECT来获取给定订单的最后状态，这里我认为有问题。

当我从整个查询中删除订单状态 table 时，执行时间快了几倍 0.152 秒

你能给我一些建议吗我怎样才能优化我的查询

给你sql解释

id  select_type        table type   possible_keys    key      key_len ref                            rows  Extra
1   PRIMARY            epi   ALL    nProductID                                                        408  Using where; Using temporary; Using filesort
1   PRIMARY            ep    eq_ref PRIMARY,nUID     PRIMARY        4 dragoni_zfms.epi.nProductID       1  Using where
1   PRIMARY            em    eq_ref PRIMARY          PRIMARY        4 dragoni_zfms.ep.nManufacturerID   1 
1   PRIMARY            t_u   eq_ref PRIMARY          PRIMARY        4 dragoni_zfms.ep.nUserLockID       1 
1   PRIMARY            eop   ref    id_productid     id_productid   5 dragoni_zfms.ep.nUID             13 
1   PRIMARY            eo    eq_ref PRIMARY          PRIMARY        4 dragoni_zfms.eop.nOrderID         1  Using index
1   PRIMARY            eos   eq_ref PRIMARY,nOrderID PRIMARY        4 func                              1  
2   DEPENDENT SUBQUERY eos   ref    nOrderID         nOrderID       4 dragoni_zfms.eo.nUID              1  Using where; Using index; Using filesort

Answer 1

在您的情况下，不使用 mysql 而使用 php 执行某些操作会更容易。当你赢得时间时，我在我的实践案例中看到过。请尝试将一个复杂的查询分成几个简单的查询。然后使用 php 脚本执行必要的过滤。希望能帮助到你。谢谢！

需要帮助优化 MySQL 具有少量连接的查询

Need Help for Optimizing MySQL query with few joins

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database-optimization