how compare and exclude the values from different table

[PrajS]

Hi there,

I have loaded 3 Tables,  'Orders' , Table A and Table B all having OrderID as key column 

I need Count of orderID from Orders table that are not in Table A or Table B. 

Something like below (where OrderID is from Orders table)

COUNT( {$<

[OrderID]=e({<[OrderID]= p([OrderID_A]) >} [OrderID]),
[OrderID]=e({<[OrderID]= p([OrderID_B]) >} [OrderID]) >} [OrderID])>}

DISTINCT [OrderID]) 

Any help is really appreciated.

COUNT( {$<

[OrderID]=e({<[OrderID]= p([OrderID_A]) >} [OrderID]),
[OrderID]=e({<[OrderID]= p([OrderID_B]) >} [OrderID]) >} [OrderID])>}

DISTINCT [OrderID]) 

Thank You 

[PrajS]

Found an expression 

Count(

{$<[OrderDate]=P([Report Date])
*
e({<[OrderID]= p([OrderID_A])>}[OrderID])
*
e({<[OrderID]= p([OrderID_B])>}[OrderID])
>}

DISTINCT [OrderID])

But Its not giving the desired result. 

Looking forward for an answer