Question

我有一个名为ntr_perf的表，其中包含以下列：data，cos，network，tot_reg，tot_rej。我需要为每对data-cos得到tot_reg和tot_rej的总和（我需要获取所有数据 - cos对，并使用相同的数据为所有网络建立值的总和 - cos对）。

我使用以下MySQL查询：

SELECT DISTINCT 
    data AS d, 
    cos AS c, 
    (SELECT SUM(tot_reg) FROM ntr_perf WHERE data=d AND cos=c) AS sumattempts, 
    (SELECT SUM(tot_rej) FROM ntr_perf WHERE data=d AND cos=c) AS sumrej FROM ntr_perf

即使表只有91.450行（表中有多列索引数据 - cos），也需要很长时间。

是否可以加快查询速度？

Answer 1

这正是group by的设计目标。

试试这个：

SELECT data,cos,SUM(tot_reg),SUM(tot_rej) from ntr_perf group by data,cos

Answer 2

您可以使用此查询

SELECT data AS d, cos AS c,
SUM(tot_reg), SUM(tot_reg) where 
data='d' AND cos='c' group by data , cos ;

希望你有。另外请告诉我，会帮助你

Answer 3

试试这个，一个小组

SELECT data d,
       cos c,
       SUM(tot_reg) sumattempts,
       SUM(tot_rej) sumrej
FROM ntr_perf 
WHERE data = 'd'  -- if these are values, put in single quotes
AND cos = 'c' -- if these are values, put in single quotes
GROUP BY data, -- even though aliased, the original name needs to be used on the GROUP BY
         cos -- even though aliased, the original name needs to be used on the GROUP BY

Answer 4

这会将您的查询分组并过滤您的总和，因为您发布了WHERE条件：

SELECT 
    data AS d, 
    cos AS c,
    SUM(IIF(data='d' AND cos='c', tot_reg, 0) AS sumattempts,
    SUM(IIF(data='d' AND cos='c', tot_rej, 0)) AS sumrej 
FROM 
    ntr_perf 
GROUP BY 
    data,
    cos

加速SQL嵌套查询

4 个答案: