防止CheckBoxList的VB.NET插入重复数据

Question

问候！ 我有我的网页表单中的CheckBoxList项目。它已经做工精细，但我想，以防止它相同的数据（一式两份）插入到表中。 这里是我的代码：

Using conn2 As New SqlConnection()
        conn2.ConnectionString = ConfigurationManager _
            .ConnectionStrings("BackboneConnectionString").ConnectionString()
        Using cmd As New SqlCommand
            cmd.CommandText = "Insert into EL_MstFunctionalNilai values(@IDFunc, @nik, @IDFuncParent, @IDFuncChild, @IDFuncMtr, '', '', '0')"
            cmd.Connection = conn2
            conn2.Open()
            For Each item As ListItem In CheckBoxList2.Items
                If item.Selected Then

                    Dim urutan As Int32 = GetNumberFunctional()
                    Dim str As String = item.Value.ToString

                    Dim strArr() As String = str.Split("_")
                    Dim IDFunctionalParent1 As String = strArr(0)
                    Dim IDFunctionalChild1 As String = strArr(1)
                    Dim IDFunctionalMtr1 As String = strArr(2)

                    cmd.Parameters.Clear()
                    cmd.Parameters.AddWithValue("@IDFunc", urutan)
                    cmd.Parameters.AddWithValue("@nik", txtnik.Text)
                    cmd.Parameters.AddWithValue("@IDFuncMtr", IDFunctionalMtr1) 'mtr
                    cmd.Parameters.AddWithValue("@IDFuncParent", IDFunctionalParent1) 'parent 
                    cmd.Parameters.AddWithValue("@IDFuncChild", IDFunctionalChild1) 'child

                    cmd.ExecuteNonQuery()

                End If
            Next
            conn2.Close()
        End Using
    End Using

NB。 “聂”是雇员ID - >所以1名员工不会得到重复数据 如何检查是否“IDFunctionalParent1”和“IDFunctionalChild1”和“IDFunctionalMtr1”存在于表（PARAM：“聂”）之前，将它们插入到表？ 干杯

Answer 1

在INSERT语句中使用

coalesce((select max(id)+1 from table),0)

如果我把它放在你的代码

Insert into EL_MstFunctionalNilai values(coalesce((select max(id)+1 from EL_MstFunctionalNilai),0), @nik, @IDFuncParent, @IDFuncChild, @IDFuncMtr, '', '', '0')

0是，如果默认值返回NULL