Question

我的kriteria数据库的列名kode包含kriteria 1到kriteria 6的值{/ p>

我希望用户可以从kode中选择3到6个值，它会在datagridview中显示为矩阵......

如果用户选择6 kriteria，则没有问题，它显示矩阵6x6 like this
...但如果用户选择少于6个kriteria或参数为空，则不显示任何内容......

这是我的代码

Private Sub perhitungankriteria_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        For Each item In menuuser.ListBox2.Items
            list2.Add(item)
        Next
        connect()

    End Sub

    Sub connect()
        Dim adapter As OleDbDataReader
        Dim cmd As OleDbCommand
        cmd = New OleDbCommand("SELECT kode FROM kriteria WHERE kode=@kriteria1 OR kode=@kriteria2 OR kode=@kriteria3 OR kode=@kriteria4 OR kode=@kriteria5 OR kode=@kriteria6", konek)
        cmd.Parameters.Add("@kriteria1", OleDbType.VarChar, 50).Value = list2(0)
        cmd.Parameters.Add("@kriteria2", OleDbType.VarChar, 50).Value = list2(1)
        cmd.Parameters.Add("@kriteria3", OleDbType.VarChar, 50).Value = list2(2)
        cmd.Parameters.Add("@kriteria4", OleDbType.VarChar, 50).Value = list2(3)
        cmd.Parameters.Add("@kriteria5", OleDbType.VarChar, 50).Value = list2(4)
        cmd.Parameters.Add("@kriteria6", OleDbType.VarChar, 50).Value = list2(5)
        adapter = cmd.ExecuteReader

        DataGridView1.Columns.Clear()

        While adapter.Read
            list.Add(adapter("kode"))
            DataGridView1.Columns.Add(adapter("kode"), adapter("kode"))
        End While

我在sql SELECT语句中尝试IN而不是WHERE查询但是出现了同样的问题

Answer 1

在用户从列表框中进行选择后，从按钮单击调用BuildCommand。

Dim list2() As String = {"kriteria1", "kriteria2", "kriteria3", "kriteria4", "kriteria5", "kriteria6"}
    Private Sub Form4_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ListBox1.DataSource = list2

Private Sub BuildCommand()
        Dim sb As New StringBuilder("SELECT kode FROM kriteria WHERE kode = ")
        Dim ct As Integer = ListBox1.SelectedItems.Count
        Dim cn As New OleDbConnection("Your connection string")
        Dim cmd As New OleDbCommand
        cmd.Parameters.Add("@kriteria1", OleDbType.VarChar, 50).Value = list2(0)
        cmd.Parameters.Add("@kriteria2", OleDbType.VarChar, 50).Value = list2(1)
        cmd.Parameters.Add("@kriteria3", OleDbType.VarChar, 50).Value = list2(2)
        cmd.Parameters.Add("@kriteria4", OleDbType.VarChar, 50).Value = list2(3)
        cmd.Parameters.Add("@kriteria5", OleDbType.VarChar, 50).Value = list2(4)
        cmd.Parameters.Add("@kriteria6", OleDbType.VarChar, 50).Value = list2(5)
        If ListBox1.SelectedItems.Contains(ListBox1.Items(0)) Then
            sb.Append("@kriteria1 OR kode = ")
        End If
        If ListBox1.SelectedItems.Contains(ListBox1.Items(1)) Then
            sb.Append("@kriteria2 OR kode = ")
        End If
        If ListBox1.SelectedItems.Contains(ListBox1.Items(2)) Then
            sb.Append("@kriteria3 OR kode = ")
        End If
        If ListBox1.SelectedItems.Contains(ListBox1.Items(3)) Then
            sb.Append("@kriteria4 OR kode = ")
        End If
        If ListBox1.SelectedItems.Contains(ListBox1.Items(4)) Then
            sb.Append("@kriteria5 OR kode = ")
        End If
        If ListBox1.SelectedItems.Contains(ListBox1.Items(5)) Then
            sb.Append("@kriteria6;")
        End If
        Dim strSQL As String = sb.ToString
        If strSQL.EndsWith("= ") Then
            Dim index As Integer = strSQL.LastIndexOf("O") 'last capital O
            strSQL = strSQL.Remove(index)
            strSQL &= ";"
        End If
        Debug.Print(strSQL) 'Check the immediate window
        cmd.CommandText = strSQL
        cmd.Connection = cn
        'use your command as you wish
    End Sub

vb.net无法在OR语句中获取数据库值

1 个答案: