让 SQL 查询更快更好
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【中文标题】让 SQL 查询更快更好【英文标题】：Make SQL query faster and better 【发布时间】：2017-03-26 21:44:50 【问题描述】：我有一个案例，我需要从包含大量聚合数据的表中收集销售统计数据。该表有几百万个条目，数据库本身约为 22Gb。大量数据可供使用！
我有这个有效的查询，但我觉得我应该做得更好 - 而且它也很慢。
我在 CentOS 7 上使用带有 sqlsrv 扩展的 php 连接到 MSSQL 数据库（ERP 系统）。
我在这个查询中的 php 变量是这样设置的：
$customer = '12345';
$year = '2016';
$compared_year = '2015';
所以，正如您可能已经猜到的那样，我正在收集 2016 年和 2015 年每个月的给定客户的销售统计数据。
SELECT
ProdTr.CustNo AS customernummer,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "01' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_1,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "02' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_2,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "03' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_3,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "04' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_4,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "05' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_5,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "06' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_6,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "07' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_7,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "08' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_8,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "09' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_9,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "10' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_10,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "11' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_11,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $year . "12' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS sum_period_12,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "01' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_1,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "02' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_2,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "03' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_3,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "04' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_4,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "05' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_5,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "06' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_6,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "07' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_7,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "08' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_8,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "09' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_9,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "10' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_10,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "10' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_11,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $year . "11' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS dg_period_12,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "01' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_1,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "02' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_2,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "03' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_3,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "04' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_4,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "05' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_5,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "06' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_6,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "07' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_7,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "08' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_8,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "09' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_9,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "10' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_10,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "11' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_11,
(SELECT SUM(DAm) AS 'Sum' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "12' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_sum_period_12,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "01' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_1,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "02' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_2,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "03' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_3,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "04' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_4,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "05' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_5,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "06' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_6,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "07' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_7,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "08' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_8,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "09' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_9,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "10' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_10,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "11' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_11,
(SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM(DAm),0)) AS 'DG' FROM ProdTr WHERE AcYrPr = '" . $compared_year . "12' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') AS compared_dg_period_12
FROM ProdTr
WHERE AcYrPr LIKE 201612
AND ProdTr.TrTp = 1
AND ProdTr.CustNo = '" . $customer . "'
GROUP BY ProdTr.CustNo, ProdTr.TrTp, ProdTr.AcYrPr
请注意，查询运行良好，给出了我期望的结果 - 但对于有很多订单/交易的客户来说，它太慢了。
关于如何加快速度的任何指示？
非常感谢您的宝贵时间！
【问题讨论】：
你看过 GROUP BY 吗？即使你不能在一个查询中运行整个事情，你也可以在一个查询中完成，比如说，四个并将结果放入一个关联数组中。 【参考方案1】：您的查询应该使用条件聚合：
SELECT ProdTr.CustNo AS customernummer,
SUM(CASE WHEN AcYrPr = '" . $year . "01' THEN DAm ELSE 0 END) as sum_period_1,
SUM(CASE WHEN AcYrPr = '" . $year . "02' THEN DAm ELSE 0 END) as sum_period_2,
. . .
WHERE AcYrPr LIKE 201612 AND ProdTr.TrTp = 1 AND
ProdTr.CustNo = '" . $customer . "'
GROUP BY ProdTr.CustNo, ProdTr.TrTp;
子查询应该不是必需的。
【讨论】：
谢谢！这在从 GROUP BY 子句中删除 ProdTr.AcYrPr 时效果很好 请问您如何放置 (SELECT (((SUM(DAm)-(SUM(StcCst)*-1))*100)/NULLIF(SUM( DAm),0)) 作为 ProdTr 的“DG”，其中 AcYrPr = '" . $year . "01' AND ProdTr.TrTp = 1 AND ProdTr.CustNo = '" . $customer . "') 作为 dg_period_1，在这种情况下句法？非常感谢！ @MagnusAlexander 。 . .我错过了group by。
别担心 :) 非常感谢！以上是关于让 SQL 查询更快更好的主要内容，如果未能解决你的问题，请参考以下文章