Finding nearest date compared to other date

[Twanne]

Hi,

I've got this query returning Longfunction and Parameters for some patients.
I select all longfunctions and when there is a matching date the parameter is displayed. But now I would like to display the parameter when I have no matching date, I'd like to see the parameter wich is taken before or after the date, depending on the time between them.

SELECT Patient.eadnr, Patient.Naam, Patient.Voornaam, longfunctie.Datum, longfunctie.FVC, longfunctie.FEV1, longfunctie.[MEF 50%], PatParameters.Parameter, PatParameters.Waarde
FROM Patient, longfunctie, PatParameters
WHERE (((Patient.eadnr)=[Longfunctie].[eadnr] And (Patient.eadnr)=[PatParameters].[eadnr] And (Patient.eadnr)=[forms]![patchoise]![eadnr]) AND ((longfunctie.Datum)=[PatParameters].[Datum]));

Greetz
Twanne

[Rabbit]

Hi,

I've got this query returning Longfunction and Parameters for some patients.
I select all longfunctions and when there is a matching date the parameter is displayed. But now I would like to display the parameter when I have no matching date, I'd like to see the parameter wich is taken before or after the date, depending on the time between them.

SELECT Patient.eadnr, Patient.Naam, Patient.Voornaam, longfunctie.Datum, longfunctie.FVC, longfunctie.FEV1, longfunctie.[MEF 50%], PatParameters.Parameter, PatParameters.Waarde
FROM Patient, longfunctie, PatParameters
WHERE (((Patient.eadnr)=[Longfunctie].[eadnr] And (Patient.eadnr)=[PatParameters].[eadnr] And (Patient.eadnr)=[forms]![patchoise]![eadnr]) AND ((longfunctie.Datum)=[PatParameters].[Datum]));

Greetz
Twanne

I don't follow. Can you explain again and provide an example? And why are you not using joins instead?