Databases
StackOverflow2013
Postsdbo
POGet a range of dates given an interval and step
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POGet a range of dates given an interval and step
    primarykey
    data
    text
    <p><strong>Edit</strong> It looks like creating a table that holds the DateTimes by minutes to join against would make the most sense. 100 years worth of minutes is ~52M rows. Indexed by the Ticks should make the query run pretty fast. It now becomes</p> <p>Thanks for the feedback everyone!</p> <p>I have a class called Recurrence that looks like this:</p> <pre><code>public class Recurrence { public int Id { get; protected set; } public DateTime StartDate { get; protected set; } public DateTime? EndDate { get; protected set; } public long? RecurrenceInterval { get; protected set; } } </code></pre> <p>It is an entity framework POCO class. There are two things I want to do with this class all with standard query operators. (So that the query runs entirely server side).</p> <p>First I want to create a query that returns all the dates from the start date to the end date inclusive with the given recurrence interval. The iterative function is simple</p> <pre><code>for(i=StartDate.Ticks; i&lt;=EndDate.Ticks; i+=RecurrenceInterval) { yield return new DateTime(i); } </code></pre> <p>Enumerable.Range() would be an option but there is no long version of Range. I'm thinking my only option here is Aggregate but I'm still not very strong with that function.</p> <p>Finally once I have that query working, I want to return the values from there that are within a time window i.e. between a different start and end date. That is easy enough to do using SkipWhile/TakeWhile.</p> <p>Here's how I could do it if DateTime.Ticks was an int</p> <pre><code>from recurrence in Recurrences let range = Enumerable .Range( (int)recurrence.StartDate.Ticks, recurrence.EndDate.HasValue ? (int)recurrence.EndDate.Value.Ticks : (int)end.Ticks) .Where(i=&gt;i-(int)recurrence.StartDate.Ticks%(int)recurrence.RecurrenceLength.Value==0) .SkipWhile(d =&gt; d &lt; start.Ticks) .TakeWhile(d =&gt; d &lt;= end.Ticks) from date in range select new ScheduledEvent { Date = new DateTime(date) }; </code></pre> <p>I guess what I need is an implementation of LongRange that could execute over an EF Query.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USMichael Brown
    1. USMichael Brown
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COIt would seem more appropriate to return dates on a daily/hourly basis rather than for every tick. How do you need to use this?
      singulars
      1. POGet a range of dates given an interval and step
      1. USMagnus
    2. COI figure that even if you could get what you want, you'll be back to ask how to improve the performance of it. When the first step is easy and the second step is defeatingly difficult, it might mean the first step was on the wrong path.
      singulars
      1. POGet a range of dates given an interval and step
      1. USAmy B
    3. COYou should consider using an existing library for Recurrence's such as [Quartz.NET](http://quartznet.sourceforge.net/) or [iCalendar](http://sourceforge.net/projects/dday-ical/)
      singulars
      1. POGet a range of dates given an interval and step
      1. USMagnus
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload