I’m a data analyst in the insurance industry and we currently have a program in SAS EG that tracks catastrophe development week by week since the start of the event for all of the catastrophic events that are reported.
(I.E week 1 is catastrophe start date + 7 days, week 2 would be end of week 1 + 7 days and so on) then all transaction amounts (dollars) for the specific catastrophes would be grouped into the respective weeks based on the date each transaction was made.
Problem that we’re faced with is we are moving away from SAS EG to GCP big query and the current process of calculating those weeks is a manually read in list which isn’t very efficient and not easily translated to BigQuery.
Curious if anybody has an idea that would allow me to calculate each week number in periods of 7 days since the start of an event in SQL or has an idea specific for BigQuery? There would be different start dates for each event.
It is complex, I know and I’m willing to give more explanation as needed. Open to any ideas for this as I haven’t been able to find anything.
Problem overview
I'm working on a simple app for reminding the user of weekly goals. Let's say the goal is to do 30 minutes of exercise on specific days of the week.
Sample goal: do exercise on Mon, Wed, Fri.
The app also needs to track past record, i.e. dates when the user did exercise. It could be just dates, e.g.: 2019-09-02, 2019-09-05, 2019-09-11 means the user did exercise on these days and did not on the others (doesn't need to be on "exercise goal" days of the week).
The goal can change in time. Let's say today is 2019-09-11 and the goal for this week ([2019-09-09, 2019-09-15]) is Mon, Wed, Fri but from 2019-08-05 to 2019-09-08 it was Mon, Thu (repeatedly for all these weeks).
I need to store these week-oriented goals and historic exercise of data and be able to retrieve the following:
The goal days for the current week (or any week, let's say I can compute start and end day for any week given a date).
Exercise history for a larger range of days together with goal days for that range (e.g. to show when the user was supposed to exercise and when they actually did in the last month).
Question
How to best store this data in SQL.
This is a little bit academic because I'm working on a small Android app and the data is just for a single user. So there will be little data and I can successfully use any approach, even a very clumsy one will be efficient enough.
However, I'd like to explore the topic and maybe learn a thing or two.
Possible solutions
Here are two approaches that come to my mind.
In both cases I would store exercise history as a table of dates. If there is an entry for that date it means the user did exercise on that day.
It's the goal storage that is interesting.
Approach 1
Store the goals per-week (it's SQLite so dates are stored as strings - all dates are just 'YEAR-MONTH-DAY'):
CREATE TABLE goals (
start_date TEXT,
exercise_days TEXT);
"start_date" is the first day of the week,
"exercise_days" is a comma-separated list of weekdays (let's say numbers 1-7).
So for the example above we might have two rows:
'2019-08-05', '1,4'
'2019-09-09', '1,3,5'
meaning that since 2019-08-05 the goal is Mon, Thu for all weeks until 2019-09-09, when the goal becomes Mon, Wed, Fri. So there is a gap in the data. I wouldn't want to generate data for weeks starting on 2019-08-12, 2019-08-19, 2019-08-26.
With this approach it is easy to work with the data week-wise. The current goal is the one with MAX('start_date'). The goal for a week for a given date is MAX('start_date') WHERE 'start_date' <= :date.
However it gets cumbersome when I want to get data for the last 3 months and show the user their progress.
Or maybe I want to show the user the percentage of actual exercise days to what they set as their goal in a year.
In this case it seems the best approach is to fetch the data separately and merge it in the application (or maybe write some complex queries), processing week by week. This is ok performance-wise because the amount of data is small and I rarely need more than a handful of weeks.
Approach 2
Store goals in such a way that each goal day is a record:
CREATE TABLE goals (
day TEXT,
);
"day" is a day when the user should exercise. So for the week starting 2019-09-09 (Mon, Wed, Fri) we would have:
'2019-09-09'
'2019-09-11'
'2019-09-13'
and for the week starting 2019-08-05 (Mon, Thu) we would have:
'2019-08-05'
'2019-08-09'
but what for the weeks in-between?
If my app could fill all the weeks in-between then it would be easy to merge this data with the exercise history and display days when the user was supposed to exercise and when they actually did. Extracting the goal for any given week would also be easy.
The problem is: this requires the app to generate data for the "gap" weeks even if the user doesn't tweak the goal. This can be implemented as a transaction that is run each time the app process starts. In some cases it could take noticeable time for occasional users of the app (think progress bar for a second).
Maybe there a smart way to generate the data in-between when making a SELECT query?
I don't like the fact that it requires generating data. I do like the fact that I can just join the tables and then process that (e.g. compute how many exercise days there were supposed to be in August and how many days the user did actually exercise and then show them percentage like "you did 85% of your goal" - in fact I can do this without joining the tables).
Also, it seems this approach gives me more flexibility for analysis in the future.
But is there a third way? Or maybe I am overthinking this? :)
(I am asking mostly for the way of organizing the data, there's no need for exact SQL queries)
Perhaps I'm over-thinking this, but if a goal can have multiple components to it, and can change over time I'd have a goal header record, with the ID, name and other data about the goal as a whole, and then a separate table linked with the components of that goal which are time-boxed, for example:
CREATE TABLE goal_days (goal_day_ID INT,
goal_ID INT,
day_ID INT,
target_minutes INT,
start_date TEXT,
end_date TEXT)
I'd have thought that allows you to easily check against the history to map against each day of the goal - e.g. they got 100% of the Mondays, but kept missing Thursday - however when the goal was changed to Friday instead they got better.
I am trying to write a sql query that would automate my reporting, I am pulling total renewal volume for month X and dividing it by the # of business days for that specific month (manual process for now). The issue that I am having and cannot seem to solve is that I report on two centers (Toronto & Montreal) and these two cities do not share the same holidays so depending on the month the # of business days will vary between cities.
The solution that I can think of is making a table within sql manually with a year or two ahead of the holidays for these 2 cities then sourcing the table, unless anyone else can suggest something better :).
Thanks in advance
I want to have a function to return the next business day of the date that is sent in as parameter.
Weekends and Canadian holidays should be included.
What is the easiest way to do this ? Is it possible to do this without setting a reference to a range of cells for the holidays' dates?
Unless you provide a list of holidays, you won't be able to calculate the next working date. Remember the rules for Easter involve the phase of the moon! So this is not a simple task.
That is before you start to consider which different countries. Even if you restrict yourself to the US holidays, it takes a fair bit of calculations just to get the 3rd Thursday in November etc
Here is a demonstration of how you could calculate the next working day.
I wouldn't hold just the holidays but every date in the calendar. Note for Easter I have fudged the holiday column to get the correct next working day answer.
You could miss a few steps in the calculation, I left them in for clarity.
Use the =WORKDAY() function. You'll have to specify a range of holidays as the third parameter.
I have a report that, according to users, started miscalculating dates in one field in November 2015. After some digging around, I found that one of the tables the field referenced seemed to have an end date on 2015-10-31.
The "D" field seems to represent the day of the week, with Sunday being day 1 and Saturday being 7.
Is there a way to extend the calendar so that it ends further into the future, for example 2049-12-31?
Our calendar table, for a variety of reasons, goes the the end of the current year. We have written a query that adds a new year to this table. This query takes care of most of the fields in that table. It does not touch the holiday field. That is updated manually through a web page.
We send ourselves reminders. Starting in March, we send monthly reminders that we should think about adding another year. After ensuring that the database segment has space, and that none of the definitions, such as fiscal periods, have changed, we run the query that adds a year.
Later in the year we start mailing ourselves reminders about the holidays. Then we check to see if HR has declared them, and if so, update the records accordingly.
This meets our business requirements. Yours will be different of course.