Dataset, try catch 的问题(vb2005)

cheewai

我的coding如下：
Private mdsAdditionalPJS As New DataSet()
Private mdsPaperCode As New DataSet()


Try
If txtJobNo.Text <> "" And e.KeyChar = Chr(13) Then
cmd = New MySqlCommand("SELECT * FROM prodjof WHERE ProdJobNo=?ProdJobNo ", conn)
cmd.Parameters.Add("?ProdJobNo", MySqlDbType.VarChar) 'Access the id datafield
cmd.Parameters("?ProdJobNo").Value = txtJobNo.Text.Trim
da.SelectCommand = cmd
da.Fill(mdsAdditionalPJS)
a = mdsAdditionalPJS.Tables(0).Rows.Count
mdsPaperCode.merge(mdsAdditionalPJS)
End If

Catch ex As Exception
MessageBox.Show(ex.Message)
End Try

1.要如何 merge dataset呢？
2.为什么 merge dataset 了有 error,而 try catch catch到了error, messagebox 没 show 出来?

cheewai

请问 dim a as dataset() 和 dim a as dataset 有什么不同？wen

也许 是 dataset schema 不一样巴