你的意思是,表B在表A上没有的行,就标为true?
For Each dr As DataRow In DataTables("表B").DataRows
Dim filter As String = "项目名称 = '" & dr("项目编号") & "' and 费用等级 = '" & dr("费用等级") & "' and 诊疗项目编号 = '" & dr("诊疗项目编号") & "'"
Dim fdr As DataRow = DataTables("表A").Find(filter)
If fdr Is Nothing Then
dr("B") = True
Else
dr("B") = False
End If
Next