สอบถามเกี่ยวกับการสร้างฟอร์มและวิธีการใช้คำสั่ง SQL เพื่อให้ User เลือกข้อมูลที่ต้องการได้

Dim sSQL As String = Trim(Me.Textbox1.Text)
objCom = New SqlCommand(sSQL, dbCon)
objCom.ExecuteNonQuery()

Sub InitialMachine()
        Dim cmd As New SqlCommand
        Dim da As New SqlDataAdapter
        Dim ds As New DataSet
        Try
            With cmd
                .Connection = mycon
                .CommandType = CommandType.Text
                .CommandText = "select MachineName from T_Machine where MachineID<>'" & TextBox1.Text & "' "
                ' .CommandText = " '" & TextBox1.Text & "' "


            End With

            da.SelectCommand = cmd
            da.Fill(ds, "Matco1_Machine") 'Keep data to Dataset
            cboMachineName.DataSource = ds.Tables("Matco1_Machine")
            cboMachineName.DisplayMember = "MachineName"
            cboMachineName.ValueMember = "MachineName"

        Catch exsql As SqlException
            MsgBox(exsql.Message, MsgBoxStyle.Exclamation)
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Exclamation)
        End Try

    End Sub

Dim sql1 As String = "SELECT * FROM SYS.TABLES ORDER BY Name"
Dim dt As New DataTable
dt = gGetDataTable(sql1)
If dt IsNot Nothing Then
            If dt.Rows.Count > 0 Then
                For Each dr As DataRow In dt.Rows
                    Me.cboTableName.Items.Add(dr("Name"))
                Next
            End If
            dt.Dispose()
            dt = Nothing
End If

Private Sub cboTableName_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboTableName.SelectedIndexChanged
        Me.lvwColumn.Items.Clear()

        Dim sql1 As String = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = " & gSQ(Me.cboTableName.Text)
        Dim dt As New DataTable
        dt = gGetDataTable(sql1)
        If dt IsNot Nothing Then
            If dt.Rows.Count > 0 Then
                Dim lvwItem As ListViewItem
                For Each dr As DataRow In dt.Rows
                    lvwItem = lvwColumn.Items.Add(dr("COLUMN_NAME"))
                Next
            End If
            dt.Dispose()
            dt = Nothing
        End If
    End Sub

Private Sub btnQuery_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnQuery.Click
        Dim tempCol As String = " "
        For i As Integer = 0 To Me.lvwColumn.Items.Count - 1
            If Me.lvwColumn.Items(i).Checked Then
                tempCol &= Me.lvwColumn.Items(i).SubItems(0).Text & ", "
            End If
        Next

        If (tempCol.Equals(" ")) Then
            Exit Sub
        End If

        Dim newStr As String = tempCol.Remove(tempCol.Length - 2, 2)
        newStr &= " "

        Dim sql1 As String = "SELECT " & newStr & " FROM " & Me.cboTableName.Text
        Dim dt As New DataTable
        dt = gGetDataTable(sql1)
        If dt IsNot Nothing Then
            Me.dgv1.DataSource = dt
            dt.Dispose()
            dt = Nothing
        End If
End Sub

Public Function gGetDataTable(ByVal pQryString As String, _
                                  Optional ByVal pConn As SqlClient.SqlConnection = Nothing, _
                                  Optional ByVal pIsSilenceMode As Boolean = False) As DataTable
        If pQryString Is Nothing OrElse pQryString.Length = 0 Then
            Return Nothing
        End If
        Dim dt As New DataTable
        Dim da As New SqlClient.SqlDataAdapter

        Dim conn As New SqlClient.SqlConnection("ตรงนี้ใส่ Connection String ของคุณลงไป")

        If pConn IsNot Nothing Then
            conn = pConn
        End If
        Try
            If conn.State <> ConnectionState.Open Then
                conn.Open()
            End If
        Catch ex As Exception
            Return Nothing
        End Try

        Try
            Dim qry As String = pQryString
            If pConn IsNot Nothing Then
                da = New SqlClient.SqlDataAdapter(qry, conn)
            Else
                da = New SqlClient.SqlDataAdapter(qry, conn)
            End If
            da.SelectCommand.CommandTimeout = 0
            da.Fill(dt)
        Catch ex As Exception
            If Not pIsSilenceMode Then
                DevExpress.XtraEditors.XtraMessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)
            End If
        Finally
            If da IsNot Nothing Then
                da.Dispose()
                GC.SuppressFinalize(da)
                da = Nothing
            End If
        End Try
        Return dt
End Function

Private Function gSQ(ByVal pText As String) As String
        Return "'" & pText.Replace("'", "") & "'"
End Function