ค้นหาข้อมูลตามรหัสสินค้าหรือว่าชื่อสินค้า คือมีเรื่องให้ทุกคนช่วยหน่อยนะค่ะ คือต้องการค้นหาข้อมูลตามรหัสสินค้าหรือว่าตามชื่อสินค้านะค่ะ

Imports System.Data
Imports System.Data.SqlClient
Imports System.Text
Public Class Form2
    Dim dr As SqlDataReader
    Dim cn As SqlConnection
    Dim cm As SqlCommand
    Dim sb As New StringBuilder
    Dim strSql As String
    Dim strCn As String = "Data Source=bkk314;Initial Catalog=DB_For_Webboard;Integrated Security=True"
    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        connection()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        connection()

        sb.Remove(0, sb.Length) '' คำสั่ง Query ข้อมูล
        sb.Append("Select productid,productname,price,qty,totalprice,datesales From Product")
        If ComboBox1.Text = "รหัสสินค้า" Then
            sb.Append(" Where (productid like '%" & TextBox2.Text & "%')")
        ElseIf ComboBox1.Text = "ชื่อสินค้า" Then
            sb.Append(" Where (productname like '%" & TextBox2.Text & "%')")
        End If
        'sb.Append(" Where  (datesales Between '" & DateTimePicker1.Value.ToString("MM/dd/yyy") & "' And '" & DateTimePicker2.Value.ToString("MM/dd/yyy") & "')")

        strSql = sb.ToString() '' เก็บใน String 
        com = New SqlCommand()

        With com
            .CommandText = strSql
            .CommandType = CommandType.Text
            .Connection = cn
            dr = .ExecuteReader()
        End With
        If dr.HasRows Then ''check dr
            Dim dtSql As DataTable
            dtSql = New DataTable()
            dtSql.Load(dr)
            With DataGridView1
                .DataSource = dtSql ''**
                'Dim i As Integer = 0 '' วิธีแรกครับ
                'Dim SumPrice As Double = 0
                'For i = 0 To DataGridView1.Rows.Count - 1
                '    SumPrice += CDbl(DataGridView1.Rows(i).Cells(4).Value)
                'Next
                'TextBox1.Text = SumPrice.ToString("#,##0.00")
                ''---------------------------------
                'Dim i2 As Integer = 0 ''วิธีที่สอง
                'Dim SumPrice2 As Double = 0
                'For i2 = 0 To dtSql.Rows.Count - 1 ''**
                '    SumPrice2 += CDbl(dtSql.Rows(i2).Item("totalprice"))
                'Next
                'TextBox1.Text = SumPrice2.ToString("#,##0.00")
            End With
        Else
            MsgBox("ไม่มีข้อมูล", MsgBoxStyle.Critical, "ผลการทำงาน")
        End If
    End Sub

    Private Sub connection()
        cn = New SqlConnection()
        With cn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strCn '' string ที่ใช้ต่อ connection
            .Open()
        End With
    End Sub
End Class