MS访问：openrecordset中的参数，并检查其是否为空

Question

I am trying something like this below

formName = "CutomerF"
 checkboxName = "Check110"
 Dim rs As DAO.Recordset
    Set rs = CurrentDb.OpenRecordset("SELECT * FROM CheckBoxT WHERE [Form Name] = " & formName & " AND [Checkbox Name] = " & checkboxName)

After the query, I want to check if rs is null or not? If it is not null then how many elements does it have? How can I do this?

Answer 1

You can see if a recordset has any records by using the BOF property. You can use the RecordCount to see how many records it has. With a DAO recordset you should use the .MoveLast method first eg

If rs.BOF Then <Do Something>

rs.MoveLast
MsgBox "There are " & rs.RecordCount & " records."

Answer 2

Use the rs.RecordCount property.

IF rs.recordCount > 0 then 
   rs.movelast
   msg "There are " & rs.recordCount & " record(s)"
end if

In DAO when you open recordset that contains records the value of RecordCount is 1. if there are no records or it cannot determine if there are records the value is 0. In ADO the if there are no records or it cannot determine the number of records RecordCount will return -1. Either way checking for greater than 0 will determine if you have records for ADO and DAO.

BOF and EOF used seperately will not work for ADO, you could do it, but then you have to make two checks. if they are both true when you open the the recordset then your recordset is empty. When an ADO recordset opens with no records both BOF and EOF are set to true. https://msdn.microsoft.com/en-us/library/windows/desktop/ms675787(v=vs.85).aspx