從一個簡單的SQL來看，CPU主頻對計算密集型SQL執行速度影響的差別，測試語句有三個特點：簡單SQL，計算密集型SQL，循環多次執行來放大執行時間

1，構造一個簡單的插入語句SQL

2，通過隨機排序，來模擬計算密集型操作

3，通過循環來放大執行時間

完全一樣的SQL：

10年前的4代i7，老掉牙的PC級CPU了，但是主頻高，3.6GHz主頻的CPU，2秒鐘跑完

5年前的Xeon E5620，服務器CPU，但是主頻低，2.4GHz，要6秒鐘跑完

可以發現，100000次循環的情況下，在不同主頻的CPU下，執行時間的差異還是比較大的。

declare @counter int = 0;
while @counter<100000
begin
	declare  @my_table table
	(
		c1 int,
		c2 varchar(100)
	);
	insert into @my_table 
	select top 1 c1,c2 from 
	(
		select 1 as c1,'a' as c2
		union all
		select 2 as c1,'b' as c2
		union all
		select 3 as c1,'c' as c2
		union all
		select 4 as c1,'d' as c2
		union all
		select 5 as c1,'e' as c2
		union all
		select 6 as c1,'f' as c2
		union all
		select 7 as c1,'g' as c2
		union all
		select 8 as c1,'g' as c2
		union all
		select 9 as c1,'i' as c2
		union all
		select 10 as c1,'j' as c2
	)t
	order by newid();

	set @counter = @counter + 1;
end