使用select语句中的Case和操作优化SQL查询

Question

Is there a way to optimise the query below.

It currently takes around 2 minutes to run

I'm using MS SQL. The Records_Table has nearly 9 million records. Date field is stored in 30 minute intervals and there are 60 different types of groups

declare @date datetime
set @date = convert(datetime,'16/sep/2013',104)

SELECT 
[Group],
CASE WHEN (SUM(A) + SUM(B)) = 0 THEN 0 ELSE 
CAST(SUM(C) AS decimal(18, 2)) / (SUM(A) + SUM(B)) * 100 END AS Calculation 
FROM   Records_Table
WHERE date BETWEEN @Date AND @Date + 6
GROUP BY [Group]

Note that I need a full week of data, so I've set the condition as date BETWEEN @Date AND @Date + 6

Any help will be appreciated.

Thanks

Answer 1

尝试根据Date对表进行分区，因为据我所知，您的条件主要基于Date，并且您可以简单地在Date上创建索引，但是由于有900万行，因此我更喜欢分区。

Answer 2

我建议在（Date，Group）上建立一个索引，以便针对相关日期范围优化日期，并针对限定符对分组进行分组。