Tough Modification Of Existing SQL Query

I’m trying to modify an existing SQL query that calculates actual working days between start date in tblECN and end date in tblECNDetail to do the same between start date in tblECNDetail and end date in tblECNDetail (same table).

Where I’ve gotten into a bind is with the joins of the two tables that are needed in the first query but not in the second as both fields come from the same query.

In the current working query I join about tblECN.ECNID and tblECNDetail.ECNID. In the new query I don’t think I need to create these joins at all as BOMEntryStart and BOMEntryEnd both come from the same table (tblECNDetail). I’ve bolded all references to the table no longer required for join but I don’t know which join statements I can be rid of. When trying to save I get an error in the FROM statement if I leave as is. If I get rid of the join statement I get an error

working query
SELECT [tblECN].[ECNID], [tblECN].[RelDate], [tblECNDetail].[PendDate], DateDiff("d",[tblECN].[RelDate],[tblECNDetail].[PendDate],2)- IIf([HCOUNT]>0,[HCOUNT],0) AS DaysDiff, Int([daysdiff]/7) AS Weeks, [daysdiff]-[weeks]*3+IIf(Weekday([tblECNDetail].[PendDate],2)>5,5-Weekday([tblECNDetail].[PendDate],2),0)+IIf(Weekday([tblECN].[RelDate],2)=6,1,0)-IIf(Weekday([tblECN].[RelDate],2)>Weekday([tblECNDetail].[PendDate],2),2,0)+IIf([tblECN].[RelDate]=[tblECNDetail].[PendDate],1,0) AS weekdays, Query5.HCOUNT
FROM (tblECN INNER JOIN tblECNDetail ON [tblECN].[ECNID] = [tblECNDetail].[ECNID]) LEFT JOIN [SELECT Query4.[tblECN].[ECNID], Sum(Query4.TEMPVAL) AS HCOUNT
FROM (SELECT [tblECN].[ECNID], 1 AS TEMPVAL
FROM tblHoliday, [tblECN] INNER JOIN [tblECNDetail] ON [tblECN].[ECNID] = [tblECNDetail].[ECNID]
WHERE (((tblHoliday.Holiday) Between [tblECN].[RelDate] And [tblECNDetail].[PendDate]))) AS Query4
GROUP BY Query4.[tblECN].[ECNID]]. AS Query5 ON [tblECN].[ECNID] = Query5.[tblECN].[ECNID]
WHERE ((([tblECNDetail].[PendDate]) Between [Forms]![frmDates]![StartDate] And [Forms]![frmDates]![StopDate]) AND (([tblECN].[DoNotProcess])<>"Do Not Process"));


Not working query
SELECT [tblECN].[ECNID], [tblECNDetail]., [tblECNDetail].[BOMEntryEnd], DateDiff("d",[tblECNDetail].[BOMEntryStart],[tblECNDetail].[BOMEntryEnd],2)- IIf([HCOUNT]>0,[HCOUNT],0) AS DaysDiff, Int([daysdiff]/7) AS Weeks, [daysdiff]-[weeks]*3+IIf(Weekday([tblECNDetail].[BOMEntryEnd],2)>5,5-Weekday([tblECNDetail].[BOMEntryEnd],2),0)+IIf(Weekday([tblECNDetail].[BOMEntryStart],2)=6,1,0)-IIf(Weekday([tblECNDetail].[BOMEntryStart],2)>Weekday([tblECNDetail].[BOMEntryEnd],2),2,0)+IIf([tblECNDetail].[BOMEntryStart]=[tblECNDetail].[BOMEntryEnd],1,0) AS weekdays, Query5.HCOUNT
FROM ([b]tblECN INNER JOIN tblECNDetail ON [tblECN].[ECNID] = [tblECNDetail].[ECNID]) LEFT JOIN [SELECT Query4.[tblECN].[ECNID], Sum(Query4.TEMPVAL) AS HCOUNT
FROM (SELECT [tblECN].[ECNID], 1 AS TEMPVAL
FROM tblHoliday, [tblECN] INNER JOIN [tblECNDetail] ON [tblECN].[ECNID] = [tblECNDetail].[ECNID]
WHERE (((tblHoliday.Holiday) Between [tblECNDetail].[BOMEntryStart] And [tblECNDetail].[BOMEntryEnd]))) AS Query4
GROUP BY Query4.[tblECN].[ECNID]]. AS Query5 ON [tblECN].[ECNID] = Query5.[tblECN].[ECNID]
WHERE ((([tblECNDetail].[BOMEntryEnd]) Between [Forms]![frmDates]![StartDate] And [Forms]![frmDates]![StopDate]) AND (([tblECN].[DoNotProcess])<>"Do Not Process"));

Any help is greatly approciated.