Counts over time for things that have a start date and end date

Hey Zena, it's hard to address your question if we don't know how your data is currently structured (what's the granularity? can you provide a sample dataset?)  What are the metrics you want to sho in your trend report?

If i had to guess you want to do something like the report "how many contractors were working on March 1 and your data is one row per contractor per contract and the start and end date of their engagement on that contract.  if that's the casse you need to JOIN the transactions to a date dimension using MySQL something like...

select

t.*

d.date

FROM

contractor_transactions t

INNER JOIN

date d

ON d.date between t.startDate and t.endDate

make sure your contract strat and end dates are always populated or you'll exclude rows in your JOIN

select

t.*

d.date

FROM

contractor_transactions t

INNER JOIN

date d

ON d.date between t.startDate and coalesce(t.endDate, current_date)