SQL Average Data Based on Distance - sql

Question

I'm pretty new to SQL.
I have a database with records based on road/milepoints. My goal is to get an average value every 52.8 ft along the road. My related table has data every 15 ft, this table of course has a foreign key relating it to the primary table.
If I wanted to pull out the average value every 52.8 ft, along a given milepost, how would I go about this?
Example Data:
RecID Begin_MP End_MP
100 0 0.56
RecID MP Value1 Value2
100 0 159 127.7
100 0.003 95.3 115.3
100 0.006 82.3 107
100 0.009 56.5 74.5
100 0.011 58.1 89.1
100 0.014 95.2 78.8
100 0.017 108.9 242.5
100 0.02 71.8 73.3
100 0.023 84.1 80.2
100 0.026 65.5 66.1
100 0.028 122 135.8
100 0.031 99.9 230.7
100 0.034 95.7 111.5
100 0.037 127.3 74.3
100 0.04 140.7 543.1
The first Data is an example of a Road. The second subset of data are the values I need to query out every 52.8 ft.
Thank you

Answer 1

You could group the data in 52.8 feet blocks. One way to do that is to divide the distance by 52.8, and round that to a whole number. That way, 25 belongs to group 1, 100 belongs to group 2, 110 belongs to group 3, and so on.
In SQL Server, you'd write this like:
select
52.8 * cast(dist/52.8 as int) as Distance
, avg(value1)
, avg(value2)
from YourTable
group by cast(dist/52.8 as int)
Below is an example with your data. Because the data runs from 0 to 0.04, I've made it calculate averages per 0.01 feet block:
declare #Road table (RecID int, Begin_MP float, End_MP float)
insert into #Road select 100, 0, 0.56
declare #Values table (RecID int, MP float, Value1 float, Value2 float)
insert into #Values values
(100, 0 , 159 , 127.7),
(100, 0.003, 95.3 , 115.3),
(100, 0.006, 82.3 , 107),
(100, 0.009, 56.5 , 74.5),
(100, 0.011, 58.1 , 89.1),
(100, 0.014, 95.2 , 78.8),
(100, 0.017, 108.9, 242.5),
(100, 0.02 , 71.8 , 73.3),
(100, 0.023, 84.1 , 80.2),
(100, 0.026, 65.5 , 66.1),
(100, 0.028, 122 , 135.8),
(100, 0.031, 99.9 , 230.7),
(100, 0.034, 95.7 , 111.5),
(100, 0.037, 127.3, 74.3),
(100, 0.04 , 140.7, 543.1);
select
r.RecID
, cast(v.MP/0.01 as int)*0.01 as StartMP
, AVG(v.Value1) as AvgVal1
, AVG(v.Value2) as AvgVal2
from #Road as r
left join #Values as v
on r.RecID = v.RecID
group by r.RecID, cast(v.MP/0.01 as int)
This prints:
RecID StartMP AvgVal1 AvgVal2
100 0.00 98,275 106,125
100 0.01 87,4 136,8
100 0.02 85,85 88,85
100 0.03 107,63 138,83
100 0.04 140,7 543,1