Look closer for what I posted.

>>>>Quotes Generated for Manufacturer [ ] Model [ ]
>>>> Exclude Customers who have purchased
>>>> Exclude Customers who haven't purchased
>>>> Model year from [ ] through [ ]

It may mean: Customers, who have quotes generated for the particular Model (TYPE = "QUOTE" in a table), but haven't purchased this model (don't have records with type = "SALE"). Now, if we want to exclude these customers, it mean we want to include all the rest, that doesn't sound right to me.


>>Gregory and everyone,
>>
>>Thanks a lot for your help. I asked clarifications from the client, because it is still not clear to me.
>>
>
>What is not clear ?
>
>>>But how should I translate the second possibility - Exclude Customers who haven't purchased?
>
>Excluding Customers who haven't purchased is only including those who have purchased. No ?
>
>
>
>
>
>
>
>>>>Hi everybody,
>>>>
>>>>I have the following criteria on my form:
>>>>

>>>>Quotes Generated for Manufacturer [         ]            Model         [              ]
>>>>    Exclude Customers who have purchased
>>>>    Exclude Customers who haven't purchased
>>>> Model year from [  ] through [  ]

>>>>
>>>>I'm trying to translate this into where condition.
>>>>
>>>>Exclude customers who have purchased is clear enough:
>>>>

>>>>where not exists (select 1 from myTable where Make = [] and Model = [] and Model year between [] and [])
>>>>

>>>>But how should I translate the second possibility - Exclude Customers who haven't purchased?
>>>>
>>>>Thanks in advance.
>>>
>>>When I have a situation like that, I take a sheet of paper + a pencil and move away from the keyboard
>>>
>>>When I was a student, I was taught something like algebra of sets
>>>
>>>let C be the set of customers
>>>let A be the set of customers who purchased
>>>let B be the set of customers who did not purchase
>>>
>>>It is clear that C = A + B ( where + stands for the union)
>>>
>>>A would translate to something like [where exists(..a purchase..)]
>>>B would translate to [where not exists(.. a purchase.)
>>>
>>>excluding A = not A becomes [ not exists()]
>>>excluding B = not B becomes [ not not exists()] or simply [exists()]
>>>
>>>Excluding both A and B becomes the empty set or [ where false ]
>>>
>>>
>>>Might be simpler to understand if you were asking
>>>- include Customers who have purchased
>>>- include Customers who haven't purchased
>>>
>>>then including both of them becomes [ where ( A or B )]
>>>Since we know that C = A + B, it becomes [ where true ] (or no condition at all )
>>>
>>>
>>>
>>>In addition: A equals not B and B equals not A - since A + B = C
>>>
>>>
>>>Update
>>>There's also something like boolean algebra - the exclamation mark stands for not
>>>see : http://en.wikipedia.org/wiki/De_Morgan%27s_laws
>>>

>>>!( a and b) = !a or !b
>>>!( a or b ) = !a and !b
>>>
>>>excluding both a and b
>>>!a and !b = !(a or b)
>>>
>>>since
>>>(1)  a = !b
>>>(2)  b = !a
>>>(3)  c = a + b
>>>
>>>excluding both a and b
>>>!a and !b = ( !a and !!a) = !(a or !a) = !(a or b) = !(c) = nothing
>>>
>>>