I have a table (ShipJourneys) where I need to calculate the Total Fuel Consumed which is a float value. See the image below.
This value is obtained by summing all the individual consumers of fuel for a given vessel over the timeframe specified. This data is contained in a second table.
Boxed in area in red shows there were 5 fuel consumers (specified by the FK_RmaDataSumsystemConfigID) and that 3 of the consumers had burned 0 units of fuel and 2 had each burned 29.
To calculate the totalFuelConsumed for that range of time frames, for a given vessel (stipulated by the FK_RmaID), the following query could be used
Select sum(FuelCalc)
from FuelCalc
where Timestamp >= '2019-07-24 00:00:00'
and Timestamp <= '2019-07-24 00:02:00'
and FK_RmaID = 660
Using something like the query below does not work, resulting in bogus values
UPDATE ShipJourneys
SET TotalFuelConsumed =
(Select sum(FuelCalc) from FuelCalc as f
WHERE f.timestamp >= StartTimeUTC
and f.timestamp <= EndTimeUTC
and f.FK_RmaID = FK_RmaID)
Any suggestions on how I could join them
You could try something like that:
UPDATE myTable // Put the table correct name here
SET TotalFuelConsumed =
Select sum(FuelUsed) from FuelTimeTbl as fuelTbl
WHERE fuelTbl.timestamp >= '2019-10-21 22:13:55.000'
and fuelTbl.imestamp <= '2019-11-27 17:10:58.000'
and fuelTbl.FK_RmaID = myTable.RmaID // Put the correct attribute name
Related
I want to reduce the number of queries I'm making to my postgres database.
Currently I have this
select * from token_balances where asset_id = '36f813e4-403a-4246-a405-8efc0cbde76a' AND tick < yesterday ORDER BY tick DESC LIMIT 1;
select * from token_balances where asset_id = '36f813e4-403a-4246-a405-8efc0cbde76a' AND tick < last_week ORDER BY tick DESC LIMIT 1;
Is there some way I can make this into one query. Or is there even any need to reduce it?
Thanks
You can simply use the query with the greater date of tick. The first query already includes the results coming from the second one.
Just use the first query and you are good to go.
select * from token_balances where asset_id = '36f813e4-403a-4246-a405-8efc0cbde76a' AND tick < '2022-05-26T14:13:42.914Z' ORDER BY tick DESC LIMIT 1;
Rather than use yesterday (which is a valid reference) and last_week (which is not valid) just convert to date arithmetic. You can use simple date subtraction:
select *
from token_balances
where asset_id = '36f813e4-403a-4246-a405-8efc0cbde76a'
and tick < current_date - :num_days
order by tick desc
limit 1;
I have this sample database:
Table 1:
Type Condition_weight Price
A >50 1000
A >10 & <50 500
A <10 100
As I remember, I can do a comparison on the Condition_weight without doing too much on query.
My expectation query is something like this:
select Price from Table_1
where Type = 'A'
and {my_input_this_is a number} satisfy Condition_weight
I read it somewhere about this solution but cant find it again.
You can create a function that returns true - you will have to do the logic to extract min and max and compare value.
pseudo code...
CREATE FUNCTION conditionWeightIsSatisfed(number weight)
BEGIN
set #minValue = 0;
set #MaxValue = 1000;
..... do your conversion of the text values.....
select weight >= #minValue and weight <= #maxValue
END
id datetime new_column datetime_rankx
1 12.01.2015 18:10:10 12.01.2015 18:10:10 1
2 03.12.2014 14:44:57 03.12.2014 14:44:57 1
2 21.11.2015 11:11:11 03.12.2014 14:44:57 2
3 01.01.2011 12:12:12 01.01.2011 12:12:12 1
3 02.02.2012 13:13:13 01.01.2011 12:12:12 2
3 03.03.2013 14:14:14 01.01.2011 12:12:12 3
I want to make new column, which will have minimum datetime value for each row in group by id.
How could I do it in Power BI desktop using DAX query?
Use this expression:
NewColumn =
CALCULATE(
MIN(
Table[datetime]),
FILTER(Table,Table[id]=EARLIER(Table[id])
)
)
In Power BI using a table with your data it will produce this:
UPDATE: Explanation and EARLIER function usage.
Basically, EARLIER function will give you access to values of different row context.
When you use CALCULATE function it creates a row context of the whole table, theoretically it iterates over every table row. The same happens when you use FILTER function it will iterate on the whole table and evaluate every row against the filter condition.
So far we have two row contexts, the row context created by CALCULATE and the row context created by FILTER. Note FILTER use the EARLIER to get access to the CALCULATE's row context. Having said that, in our case for every row in the outer (CALCULATE's row context) the FILTER returns a set of rows that correspond to the current id in the outer context.
If you have a programming background it could give you some sense. It is similar to a nested loop.
Hope this Python code points the main idea behind this:
outer_context = ['row1','row2','row3','row4']
inner_context = ['row1','row2','row3','row4']
for outer_row in outer_context:
for inner_row in inner_context:
if inner_row == outer_row: #this line is what the FILTER and EARLIER do
#Calculate the min datetime using the filtered rows
...
...
UPDATE 2: Adding a ranking column.
To get the desired rank you can use this expression:
RankColumn =
RANKX(
CALCULATETABLE(Table,ALLEXCEPT(Table,Table[id]))
,Table[datetime]
,Hoja1[datetime]
,1
)
This is the table with the rank column:
Let me know if this helps.
I am trying to calculate the average of a column in Tableau, except the problem is I am trying to use a single date value (based on filter) from another data source to only calculate the average where the exam date is <= the filtered date value from the other source.
Note: Parameters will not work for me here, since new date values are being added constantly to the set.
I have tried many different approaches, but the simplest was trying to use a calculated field that pulls in the filtered exam date from the other data source.
It successfully can pull the filtered date, but the formula does not work as expected. 2 versions of the calculation are below:
IF DATE(ATTR([Exam Date])) <= DATE(ATTR([Averages (Tableau Test Scores)].[Updated])) THEN AVG([Raw Score]) END
IF DATEDIFF('day', DATE(ATTR([Exam Date])), DATE(ATTR([Averages (Tableau Test Scores)].[Updated]))) > 1 THEN AVG([Raw Score]) END
Basically, I am looking for the equivalent of this in SQL Server:
SELECT AVG([Raw Score]) WHERE ExamDate <= (Filtered Exam Date)
Below a workbook that shows an example of what I am trying to accomplish. Currently it returns all blanks, likely due to the many-to-one comparison I am trying to use in my calculation.
Any feedback is greatly appreciated!
Tableau Test Exam Workbook
I was able to solve this by using Custom SQL to join the tables together and calculate the average based on my conditions, to get the column results I wanted.
Would still be great to have this ability directly in Tableau, but whatever gets the job done.
Edit:
SELECT
[AcademicYear]
,[Discipline]
--Get the number of student takers
,COUNT([Id]) AS [Students (N)]
--Get the average of the Raw Score
,CAST(AVG(RawScore) AS DECIMAL(10,2)) AS [School Mean]
--Get the number of failures based on an "adjusted score" column
,COUNT([AdjustedScore] < 70 THEN 1 END) AS [School Failures]
--This is the column used as the cutoff point for including scores
,[Average_Update].[Updated]
FROM [dbo].[Average] [Average]
FULL OUTER JOIN [dbo].[Average_Update] [Average_Update] ON ([Average_Update].[Id] = [Average].UpdateDateId)
--The meat of joining data for accurate calculations
FULL OUTER JOIN (
SELECT DISTINCT S.[Id], S.[LastName], S.[FirstName], S.[ExamDate], S.[RawScoreStandard], S.[RawScorePercent], S.[AdjustedScore], S.[Subject], P.[Id] AS PeriodId
FROM [StudentScore] S
FULL OUTER JOIN
(
--Get only the 1st attempt
SELECT DISTINCT [NBOMEId], S2.[Subject], MIN([ExamDate]) AS ExamDate
FROM [StudentScore] S2
GROUP BY [NBOMEId],S2.[Subject]
) B
ON S.[NBOMEId] = B.[NBOMEId] AND S.[Subject] = B.[Subject] AND S.[ExamDate] = B.[ExamDate]
--Group in "Exam Periods" based on the list of periods w/ start & end dates in another table.
FULL OUTER JOIN [ExamPeriod] P
ON S.[ExamDate] = P.PeriodStart AND S.[ExamDate] <= P.PeriodEnd
WHERE S.[Subject] = B.[Subject]
GROUP BY P.[Id], S.[Subject], S.[ExamDate], S.[RawScoreStandard], S.[RawScorePercent], S.[AdjustedScore], S.[NBOMEId], S.[NBOMELastName], S.[NBOMEFirstName], S.[SecondYrTake]) [StudentScore]
ON
([StudentScore].PeriodId = [Average_Update].ExamPeriodId
AND [StudentScore].Subject = [Average].Subject
AND [StudentScore].[ExamDate] <= [Average_Update].[Updated])
--End meat
--Joins to pull in relevant data for normalized tables
FULL OUTER JOIN [dbo].[Student] [Student] ON ([StudentScore].[NBOMEId] = [Student].[NBOMEId])
INNER JOIN [dbo].[ExamPeriod] [ExamPeriod] ON ([Average_Update].ExamPeriodId = [ExamPeriod].[Id])
INNER JOIN [dbo].[AcademicYear] [AcademicYear] ON ([ExamPeriod].[AcademicYearId] = [AcademicYear].[Id])
--This will pull only the latest update entry for every academic year.
WHERE [Updated] IN (
SELECT DISTINCT MAX([Updated]) AS MaxDate
FROM [Average_Update]
GROUP BY[ExamPeriodId])
GROUP BY [AcademicYear].[AcademicYearText], [Average].[Subject], [Average_Update].[Updated],
ORDER BY [AcademicYear].[AcademicYearText], [Average_Update].[Updated], [Average].[Subject]
I couldn't download your file to test with your data, but try reversing the order of taking the average ie
average(IF DATE(ATTR([Exam Date])) <= DATE(ATTR([Averages (Tableau Test Scores)].[Updated]) then [Raw Score]) END)
as written, I believe you'll be averaging the data before returning it from the if statement, whereas you want to return the data, then average it.
How do I get the largest value in a column under a constant?
Specifically, in a table with a column of speed values how can I get the row with largest speed, under an arbitrary limit (say, 1200 mph)?
Thanks
Get a list of all the rows that fall below your maximum, then ORDER BY speed and LIMIT 1.
SELECT *
FROM your_table
WHERE speed < 1200
ORDER BY speed DESC
LIMIT 1;
If no row satisfies your criteria (i.e. the table is empty or every row has a speed larger than 1200), the query will return no rows. You should be prepared to handle this eventuality.
Unless I'm missing something, this is a simple max() with a where condition:
select max(speed)
from some_table
where speed < 1200;