Determining whether date in one table falls between dates in another table - reporting-services

Question

I have two columns of dates, the first column is the date a purchase order was received to be inspected, the second is the date that purchase order was accepted or rejected. What I would like is a graph with dates on the X-axis, and then the number of purchase orders in the queue on that day on the Y-axis.
Some purchase orders are completed that day, so they would still be counted, but they might not get addressed for days or weeks, so they would be counted on all those days until they were addressed.
Sample data below:
Row ID Date In Date Out
1 9/1/18 9/1/18
2 9/1/18 9/1/18
3 9/1/18 9/2/18
4 9/1/18 9/3/18
1 9/2/18 9/2/18
2 9/2/18 9/4/18
So, it would be 4 for 9/1/18, 4 for 9/2/18, 2 for 9/3/18, and 1 for 9/4/18.
I asked a similar question for Excel, and had success with that. However, we would like the data to be generated from within our ERP system (as opposed to copying the data to Excel manually), and I thought this might be possible using SQL and SSRS.
The formula for Excel was =COUNTIFS($A$1:$A$1000,"<="&C1,Sheet1!$B$1:$B$1000,">="&C1), so A and B were the Date In and Date Out columns, respectively, and then C was a column of all the days for the year.
I am not sure how I would a query like this, so I've started by making it similar to the Excel solution. I generated a list of dates, and I am trying to compare a date in that list to my dataset of purchase order dates, but I'm not sure how to do that, since it's comparing one (row by row) to many.

Answer 1

You need to create a table of dates and then join it to your orders based on the date being between the Date In and Date Out so that they are counted in multiple days.
DECLARE #START_DATE AS DATE = '2018-09-01'
DECLARE #END_DATE AS DATE = '2018-09-30'
IF OBJECT_ID('tempdb..#DATES') IS NOT NULL DROP TABLE #DATES;
IF OBJECT_ID('tempdb..#ORDERS') IS NOT NULL DROP TABLE #ORDERS;
SELECT 1 AS ROW_ID, CAST('2018-09-01' AS DATE) AS DATE_IN, CAST('2018-09-01' AS DATE) AS DATE_OUT
INTO #ORDERS
UNION
SELECT 2 AS ROW_ID, CAST('2018-09-01' AS DATE) AS DATE_IN, CAST('2018-09-01' AS DATE) AS DATE_OUT
UNION
SELECT 3 AS ROW_ID, CAST('2018-09-01' AS DATE) AS DATE_IN, CAST('2018-09-02' AS DATE) AS DATE_OUT
UNION
SELECT 4 AS ROW_ID, CAST('2018-09-01' AS DATE) AS DATE_IN, CAST('2018-09-03' AS DATE) AS DATE_OUT
UNION
SELECT 1 AS ROW_ID, CAST('2018-09-02' AS DATE) AS DATE_IN, CAST('2018-09-02' AS DATE) AS DATE_OUT
UNION
SELECT 2 AS ROW_ID, CAST('2018-09-02' AS DATE) AS DATE_IN, CAST('2018-09-04' AS DATE) AS DATE_OUT
;WITH GETDATES AS (SELECT #START_DATE AS DATE1
UNION ALL
SELECT DATEADD(DAY, 1, DATE1)
FROM GETDATES
WHERE DATE1 < #END_DATE
)
SELECT *
INTO #DATES
FROM GETDATES;
SELECT DATE1, COUNT(O.ROW_ID) AS ORDERS
FROM #DATES D
LEFT JOIN #ORDERS O ON D.DATE1 BETWEEN O.DATE_IN AND O.DATE_OUT
GROUP BY D.DATE1

Answer 2

Try comparing using "ReportItems!" property. Try to write expression something like:
iif(ReportItems!DateColumnX = somevalue, "Then Do something", "Else Do Something else")
Edits:
Try something like this:
Fields!ValueFromCurrentDataset(CompareLogic like(<,>,<> etc)) LookUp( Fields!ValueFromDataset2, "DataSet2")