I could use this query to select all orders with a date on a monday:
SELECT * from orders WHERE strftime("%w", date)="1";
But as far as I know, this can't be speed up using an index, as for every row strftime has to be calculated.
I could add an additional field with the weekday stored, but I want to avoid it. Is there a solution that makes use of an index or am I wrong and this query actually works fine? (That means it doesn't have to go through every row to calculate the result.)
If you want all Mondays ever, you'd need a field or sequential scan. What you could do, is calculate actual dates for example for all Mondays within a year. The condition WHERE date IN ('2009-03-02', '2009-02-23', ...) would use index
Or as an alternative to vartec's suggestion, construct a calendar table consisting only of a date and a day name for each day in the year (both indexed) and then perform your query by doing a JOIN against this table.
Related
I have a recordset where rows have a date field.Rows are from current year and last year. I want to see the count of rows per year. That's easy. Now I'd like to have a third column with difference (count(currentYear) - count(lastYear)). Is there any way to achieve this?
thanks
It seems like you want to have the difference calculated between two members of the same date field.
If so, you might want to consider the customizeCell() API call to retrieve the count values of each year, use them to calculate the difference, and modify the necessary cells with the result.
Alternatively, you could try modifying your data set so that the lastYear and currentYear are two different fields – this, for example, would allow you to compare them within a calculated value.
I am looking to select the size of the calendar table, filtering everything before or after some date, much like a slicer does.
I am trying to compute the percentage change between prices of equity indexes between two dates: now and a year ago. The problem is that the same date last year sometimes falls on a non-trading day. In that case I want the code to select the earliest value available.
In a similar situation, where I use a slicer, I implemented this by using FIRSTNONBLANK and LASTNONBLANK functions. This way, if the slicer is set to a non-trading date the system still works.
I am very much a DAX/Power BI novice, interested in the methodology in DAX as much as addressing the current problem.
Thanks in advance.
I have a date column using which I created a "relative date" filter as follows:
Now I want to create a measure as follows:
SUM(value from another column)/total number of day in that date range.
Can someone help me how to create this measure?? Thanks!!
Assuming you Record Date field is at the day level of detail, you could do:
SUM(value from another column)/countd(record_date)
I'm trying to put together an attendance report for a school that tracks student attendance codes for that student for every day on the calendar month in a DynamicsCRM system being used as a managed service (that is to say, I build queries using FetchXML and cannot use SQL). The format for the report requires that a column for every day in the month be listed for the report. My student table that tracks this attendance however only contains records for days where an attendance value is recorded, and I do not have an object available that can return every day in a month for me.
I am looking for a solution other than hardcoding 31 columns and using conditionals to control the display of the last three day columns. Ideally, I'd like a conditional in my matrix column grouping that would look at the date value for the previously generated column and determine if the next date record from my resultset is sequentially the next day of that month, and if not, create the next sequential date, move to the next column and perform the check again until it is true. Is there a way I can do this, or another means to accomplish my goal that does not involve hard-coding day columns into a table or matrix? Right now, I have nothing; I can barely imagine how I think this should look.
What I did to solve the same issue has been to create a scheduled process each day to create a record and deactivate it.
I have then been able to distinguish actual records (the active ones) from these 'placeholders' (inactive ones) in my querying.
I need your advice on the following query that I have - Let's say that I have a table with all payments that are booked on my current account.
The details of the payment contain date of the operation and hour. I would like to extract the information in a such a way so to have next to each transaction the amount of of the balance(sum of transactions' amount) since the beginning of the day up to the current transaction. The balance for each day is reset to 0.
I was thinking to join this table to itself and find all unique operations from the joined table where the date matches and the hour is less then currently reviewed operation's hour then to use sum on the group.
Still I think that there is much more intelligent solution.
Thanks in advance
here is a sample of the table. Expected result is in the last column
My guess is that you just want a rolling sum. Making up column names and table names, you probably want something like this in your projection (your select list). You shouldn't need to do a self-join.
SUM(transaction_amount)
OVER (PARTITION BY account_number, trunc(transaction_date)
ORDER BY transaction_date) rolling_sum