sql-server - 在 vb.net 中将 varchar 转换为 gridview 选定行的 int 时出错

Question

I am deleting selected row from grid view.

使用以下代码行从 gridview 中删除，但未从数据库中删除。它显示了将 varchar 转换为 int 的错误

Private Sub dltButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles dltButton.Click
            'Dim StudentId As String
            'StudentId =
            'con.Open()
            'cmd.CommandText = "delete from KaiyumVbStudent where StudentID = '"&StudentId&"'"
            'cmd.Connection = con
            Dim i As Integer = DataGridView1.CurrentRow.Index
            DataGridView1.Rows.Remove(DataGridView1.CurrentRow)
            StudentID = CType(DataGridView1.SelectedCells(2), TextBox).Text
            con = New SqlConnection(constring)
            con.Open()
            cmd = New SqlCommand("Delete from KaiyumVbStudent where StudentID = '@StudentID'", con)
            cmd.ExecuteNonQuery()
            Call databind()
        End Sub

Answer 1

我怀疑这是因为您的参数包含引号。

也就是说，这个：

Delete from KaiyumVbStudent where StudentID = '@StudentID'

可能应该这样读（注意@StudentID周围没有引号）：

Delete from KaiyumVbStudent where StudentID = @StudentID

但是，我看不到您在代码中为@StudentID.

Answer 2

执行 where 时您可能不会收到数据类型转换错误，StudentID='1'但请同意上面的评论，因为您似乎没有设置参数值。如此有效地执行以下 SQL：

Delete from KaiyumVbStudent where StudentID = '@StudentID'