How do you want to enter the dates?
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is it using two fields in the main form that the user enter date into, then
write the sql for the sub form as:
Select * From MyTable Where MyDateField Between
forms![FormName]![FieldFromDate] And forms![FormName]![FieldToDate]
On the after update of the fields you should run me.SubformName.requery
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is it using two parameters in the query that you use as the record source in
the sub form;
Select * From MyTable Where MyDateField Between [Enter Date From here:] And
[Enter Date to here:]