试试
Dim t As Table = Tables("某表")
t.filter = "出席否='Y'"
t.sort = "出席人,场号,出席日期"
Dim r1 As Row
r1 = t.rows(0)
r1("出席多次") = 1
Dim r2 As Row
For i As Integer =1 To t.rows.count - 1
r2 = t.rows(i)
If r2("出席人") = r1("出席人") AndAlso r2("场号") = r1("场号")
r2("出席多次") = 0
Else
r2("出席多次") = 1
End If
r1 = r2
Next