表B的DataColChanged事件
If e.DataCol.name = "第一列" Then
Dim str As String = ""
For Each s As String In e.DataRow("第一列").split(",")
Dim fdr As DataRow = DataTables("表A").find("第一列 = '" & s & "'")
If fdr Is Nothing Then
str &= "空,"
Else
str &= fdr("第二列") & ","
End If
Next
e.DataRow("第二列") = str.trim(",")
End If