I am storing start and finish session timestamps on a table called 'records' 1
An individual can sign in and out multiple times in a day.
I'd like to tally up the total time accummulated each day, and display the total seconds each day. The result should have the columns EmployeeID and a column for each day. Where there are no log in or out records, it should state 0.2
Related
I have a table that looks like the following:
Account_Id
Message_ID
Message_Unix_Epoch_Timestamp
saa93319992
asds274892
1653535514
How would I write a SQL query to pull the account_id's of accounts that created at-least 10 messages within a 10 minute interval since the last year?
The output should just be the account_id's that have sent more than 10 messages in any 10 minute interval.
I have a table where the data updates every hour and I need to subtract the number of quantities as of today and what was 60 days back. How can that be done in SQL?
I have a table with 17,000 records that is ordered by time spaced in 15 minute intervals. The time values loop back onto themselves every 24 hours, so for example, I could have 100 records that are all at 1 AM, just on different days. I want to create a 'average day' by taking those 100 records at 1 am and finding the average of them for the averaged 1 am.
I don't know how to format the table to make it show up nicely here.
I'm assuming you want to calculate the average value per time interval regardless of the day in a query. You could use this SQL to group your table by Time interval only (assuming that it's separate from the date field), and average whichever fields you want to average. Do not select or group by the date field, just select and group by the time field.
SELECT TimeField
, AVG([Field1ToAverage])
, AVG([Field2ToAverage])
FROM MyTable
GROUP BY TimeField;
If the date and time fields are stored together in the same column, you will have to extract the time only:
SELECT TimeValue([DateTimeField])
, AVG([Field1ToAverage])
, AVG([Field2ToAverage])
FROM MyTable
GROUP BY TimeValue([DateTimeField]);
In my Rails app's PostgreSQL DB are records containing hourly prices for the last 10 years:
10(24 x 365) of these: "12/31/2012 01:00:00", "11.99"
The following query, groups prices by day, averages the prices in those daily groupings to create daily price averages, and returns "day", "daily average" pairs for each day:
HourlyPrice.average(:price, :group => "DATE_TRUNC('day', date)")
The problem is, the hourly prices in my source data actually reflect the price for the previous hour. So, in my data source .CSV, the day starts at the time 01:00:00 and ends at the time 24:00:00.
This conflicts with how PostgreSQL likes to save records in its DateTime column. Upon importing the CSV data, PostgreSQL converts my records containing the time 24:00:00 to 00:00:00 of the next day.
This throws off the accuracy of my Averaging Query above. To fix the query, I still want to group by day, but offset 1 hour. So, that the range averaged starts at 01:00:00 and ends with the 00:00:00 value of the next day.
Is it possible to adjust the above query to reflect this?
You could subtract one hour from date before applying the DATE_TRUNC function to it, like this:
HourlyPrice.average(:price, :group => "DATE_TRUNC('day', date - INTERVAL '1 hour')")
In my Rails app, I have two custom Rake Tasks running every 30 minutes. Task A scrapes hourly prices from the internet and saves them to a database as HourlyPrice. Task B goes into the db, takes hourly prices from each day for the last seven days, and averages them to create a new DailyAveragePrice record in a separate DB Table.
However, when running Task B, the last day's (of the seven) average price is incorrect.
After fiddling with the hourly prices of that day in an Excel spreadsheet, I see that the average price Task B is generating is the result of taking only the last three hours and averaging them.
Task B is mostly done with this single query:
averages = HourlyPrice.where('date >= ?', 7.days.ago).average(:price, :group => "DATE_TRUNC('day', date - INTERVAL '1 hour')")
I can't figure out why this is happening?
Clues
HourlyPrice has two attributes (datetime,price). Each HourlyPrice actually represents a price for the previous hour. So, source data lists a 24:00:00 price for each day which PostgreSQL does not want to import as is into a datetime column. Instead, it converts all 24:00:00 prices to 00:00:00 of the next day. To make up for this, I've tried to subtract an hour interval, as you can see in the query. Is this causing the problem?
My ActiveRecord's time zone is currently set to 'Mountain Time (US & Canada)'. That is where the price exchange is located. I have not adjusted my PostgreSQL DB's timezone, and I believe it defaults to UTC. When running Task B, I noticed that it was 9:20PM UTC, leaving three hours left in the UTC day, which might explain the averaging of only three HourlyPrices of the last of the seven days. I'll try running Task B again in the next hour to see if it will average only two hours. Update to come... Is this timezone conflict causing a problem, or is what I am doing insulated from timezones since I have my own date columns?
UPDATE - Problem identified, but how to fix?
Clue #2 is correct. It is a timezone issue. I just ran Task B again (an hour later, with 2 hours left until UTC day change), and it only averages two HourlyPrices now for the last of the seven days.
How can I fix my query above to average ONLY if there are 24 HourlyPrice records available?