Question

每当我添加一个Item时，我都会尝试检查DataGridView中的每一行，以避免重复。但是我的代码只允许我检查我添加的第一个数据。

以下是我的代码：

For Each row In BarcodePrintListGrid.Rows

    If Label44.Text = row.Cells("Barcode ID").Value Then
        MetroMessageBox.Show(Me, "Item Already Added", "System Information", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

        Label47.Text = "None"
        Label44.Text = "None"
        Label42.Text = "None"
        Label31.Text = "None"
        Label40.Text = "0"
        TextBox1.Clear()

        Exit For

    Else
        BarcodePrintListGrid.Rows.Add(Label47.Text, Label44.Text, Label42.Text, Label31.Text, Label40.Text, 1)

        MetroMessageBox.Show(Me, "Item Added to List", "System Information", MessageBoxButtons.OK, MessageBoxIcon.Information)

        Label47.Text = "None"
        Label44.Text = "None"
        Label42.Text = "None"
        Label31.Text = "None"
        Label40.Text = "0"
        TextBox1.Clear()

        Exit For
    End If

Next

Answer 1

您必须等到循环已遍历DataGridView的所有行，然后才决定是否添加该行。

尝试使用此代码：

 Dim test As Boolean = False
    For Each row In BarcodePrintListGrid.Rows
        If Label44.Text = row.Cells("Barcode ID").Value Then
            test=true
            Exit For
        End If
    Next

    if test=false then
            BarcodePrintListGrid.Rows.Add(Label47.Text, Label44.Text, Label42.Text, Label31.Text, Label40.Text, 1)

            MetroMessageBox.Show(Me, "Item Added to List", "System Information", MessageBoxButtons.OK, MessageBoxIcon.Information)
    else
            MetroMessageBox.Show(Me, "Item Already Added", "System Information", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
    end if
     Label47.Text = "None"
     Label44.Text = "None"
     Label42.Text = "None"
     Label31.Text = "None"
     Label40.Text = "0"
     TextBox1.Clear()

如何检查DataGridView中是否已存在值？

1 个答案: