Question

I have two columns in the database, project_start and project_end, and I’m in passing two fields (both optional) via a report (coded in ASP).

The pseudo code below is what I currently have:

(project_start <= search_start AND project_end <= search_start)

AND

(project_start <= search_end AND project_end >= search_end)

However what the above doesn’t pick up are projects which start before the start date, but end after the start date, projects which start after the start date but end after the end date, and also projects which start before the start date and end after the end date :S

Below is my code:

if (Request.QueryString["DateFrom"] != null && Request.QueryString["DateFrom"] != "")
        {
            DateTime dateFromFilter;

            dateFromFilter = DateTime.Parse(Request.QueryString["DateFrom"]);

            Q = from qua in qTable
                    where qua.Start_Date.Date <= dateFromFilter.Date
                    && qua.End_Date.Date >= dateFromFilter.Date
                    select qua;
        }

        //filter to date
        if (Request.QueryString["DateTo"] != null && Request.QueryString["DateTo"] != "")
        {
            DateTime dateToFilter;

            dateToFilter = DateTime.Parse(Request.QueryString["DateTo"]);

            Q= from qua in qTable
                    where qua.Start_Date.Date <= dateToFilter.Date
                    && qua.End_Date.Date >= dateToFilter.Date
                    select qua;
        }

Answer 1

If you want the projects that overlap with any part of your search range, try this:

project_start <= search_end AND project_end >= search_start

I know it looks “too simple” but it does in fact cover all the cases:

• Partial overlaps at both ends
• The project being completely inside the search range
• The search range being completely inside the project.

Update

To handle optional paramaters:

(search_end IS NULL OR project_start <= search_end) AND
(search_start IS NULL OR project_end >= search_start)