一种非常简单的方法是将组合的绑定列设置为 *：

 SELECT "*" As ID, "Select All" As AText 
 FROM Table1 
 UNION SELECT Table1.ID, Table1.AText 
 FROM Table1;

使用你的组合：

 Select "*" As TreatmentID, "<<All Records>>" As Treatment 
 FROM Treatment 
 UNION 
 Select Treatment.TreatmentID, Treatment.Treatment 
 From Treatment;

然后，您可以使用 LIKE：

SELECT Table1.ID
FROM Table1
WHERE Table1.ID Like [forms]![MainForm]![Combo]

使用您的 SQL：

... WHERE (((Addresses.TreatmentID) 
  Like [Forms]![ReportCentre]![cboTreatmentType]) AND ...

如果您只有一列，则可以使用：

SELECT Table1.Atext
FROM Table1
WHERE AText Like 
   IIf(Forms![MainForm]!Combo="Select All","*",Forms![MainForm]!Combo)