Question

我需要在用户输入插入数据集之前检查它。这是我的代码。

           If ds.Tables(0).Rows.Count > 0 Then
                foundRows = ds.Tables(0).Select("AccessionNumber = '" + txtaccn.Text + "'")
            End If

            If book.checkifaccnexist(txtaccn.Text) = 1 Then
                If foundRows Is Nothing Then
                    dt.Rows.Add(New Object() {txtaccn.Text})
                    acn = acn.Insert(acn.Length, (" OR accn = '" + Label1.Text + "'"))
                    txtaccn.Clear()

                Else
                    MetroFramework.MetroMessageBox.Show(Me, "The accession number you've inputed is already in the list", "Library Management System", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                    txtaccn.Clear()
                End If
            Else

                MetroFramework.MetroMessageBox.Show(Me, "Accession Number Doesn't exist", "Library Management System", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                txtaccn.Clear()
            End If

此代码的问题是即使我在txtaccn.text中输入了不同的数字， foundRows

Answer 1

我猜问题就在于行

If foundRows Is Nothing Then

也许尝试这可能会有所帮助，

If foundRows.Length = 0 Then
'Add to DataTable

VB.NET：如何在添加之前检查数据集中是否存在输入

1 个答案: