SQL - Getting more data with a GROUP BY - sql

Question

Hoping someone can help me out with this.
Lets say I have a table called incoming_data with 4 columns:
primary_key_id
serial_number
counter
selected_color
I get data from a source that fills this table. The primary key has its identity
turned on so it is not repeating. I will get duplicate serial numbers with different selected colors.
The counter is ever increasing coming from the device.
So what I want to do is select all the data I received today, group the data by serial number and only get the record
with the highest counter value.
Simple:
SELECT serial_number, MAX(counter)
FROM incoming_data
GROUP BY serial number
This works perfectly, except that I want to do something with the color information
that I received.
If I add color to the select, then I get ALL the records since all
the colors I received that day are different. That wont work.
If I could get the primary_key_id of the record then I could just
query for the color but this doesn't work either since each primary_key_id
value is different I get them all.
Any suggestions on a better technique for doing this?
Thanks!

Answer 1

Extract the relevant key, then join back to get "non key".
This works in MS SQL Server and later Sybase.
SELECT
i.serial_number, i.counter, i.selected_color
FROM
(
SELECT serial_number, MAX(counter) AS maxc
FROM incoming_data
GROUP BY serial number
) max
JOIN
incoming_data i ON max.serial_number = i.serial_number AND max.maxc = i.counter

Answer 2

EDIT: t odeal with cases where multiple records have same serial number and max counter value.. This will extract the one of those multiples with the biggest primary_key_id
Select * From incoming_data
Where primary_key_id In
(Select Max(primary_key_id) From incoming_data I
Where Counter =
(Select Max(counter) From incoming_data
Where SerialNumber = I.SerialNumber)
Group By SerialNumber)

Answer 3

Hi I think this might do what you want?
SELECT selected_color, serial_number, counter
FROM incoming_data
GROUP BY serial_number
ORDER BY counter DESC
LIMIT 1;

Answer 4

If you don't need the exact color from the query, but could parse it afterwards, try this:
SELECT serial_number, MAX(counter), MAX( CONCAT(counter, ':', selected_color) )
FROM incoming_data
GROUP BY serial number

Answer 5

I am trying to get the max numbers from two joined tables. I tried to use DISTINCT to avoid repeatative numbers, but failed. Then I found the following query and works perfect on single table, but I failed to have it worked on joined two tables.
How to implement the following query on my query:
select top 10 ConsumptionKWH
from PeriodicConsumptions
group by ConsumptionKWH
order by min(ConsumptionKWH) asc
Needed on:
" SELECT * FROM " & _
" (SELECT Distinct top 10 " & _
" PeriodicConsumptions.ConsumptionKWH, " & _
" MeterReadings.MeterNo, " & _
" MeterReadings.LastKWH," & _
" MeterReadings.AccountNo, " & _
" MeterReadings.MultiplyFactor," & _
" MeterReadings.LastReading, " & _
" MeterReadings.ThisMonthReading," & _
" MeterReadings.NumberofDays," & _
" MeterReadings.ReadingGYear, " & _
" MeterReadings.ReadingGMonth, " & _
" MeterReadings.ReadingDate " & _
" FROM MeterReadings, PeriodicConsumptions" & _
" Where MeterReadings.AccountNo = PeriodicConsumptions.AccountNo " & _
" and MeterReadings.ReadingGYear =PeriodicConsumptions.ConsumptionYear " & _
" and MeterReadings.ReadingGMonth =PeriodicConsumptions.ConsumptionMonth " & _
" and MeterReadings.ReadingDate = PeriodicConsumptions.FromDate " & _
" ORDER BY PeriodicConsumptions.ConsumptionKWH desc) as t " & _
" ORDER BY ConsumptionKWH asc"
Thanks