使用串列框從SQL獲取影像到圖片框VB

我正在嘗試使用 VB 中的 Listbox 將影像從 SQL 獲取到圖片框。

這是我的 sql 示例表。

這是我的 VB 設計表單，所以我想要做的是當我加載表單時，如果選擇了串列框中的一個專案，我希望它從 sql 中獲取影像（二進制資料）到 VB 網路中的圖片框.

我正在使用它的代碼給了我這個錯誤：

VB完整代碼：

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    connect()
    Dim co As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True")
    co.Open()
    Dim com As New SqlCommand("SELECT Image from Items where ItemName = '" & ListBox1.SelectedIndex & "'", co)
    Dim img As Byte() = DirectCast(com.ExecuteScalar(), Byte())
    Dim ms As MemoryStream = New MemoryStream(img)

    Dim dt = GetDataFromSql()
    Dim BndSrc As New BindingSource()
    BndSrc.DataSource = dt
    ListBox1.DisplayMember = "ItemName"
    ListBox1.DataSource = BndSrc
    TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
    TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
    TextBox3.DataBindings.Add("Text", BndSrc, "Details")
    PictureBox1.Image = Image.FromStream(ms)

End Sub
Private Function GetDataFromSql() As DataTable
    Dim dt As New DataTable
    Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
            cmd As New SqlCommand("select * FROM Items", connection)
        connection.Open()
        Using reader = cmd.ExecuteReader
            dt.Load(reader)
        End Using
    End Using
    Return dt
End Function

uj5u.com熱心網友回復：

從Form.Load. 我們已經選擇了GetDataFromSql函式中的所有資料。魔法發生在ListBox1.SelectedIndexChanged方法中。

該SelectedIndexChanged會發生作為代碼的結果，Form.Load每一個選擇改變時間和金錢。當我們將串列框系結到系結源時，整行都被添加為DataRowView. 我們可以使用它來獲取 Image 列中的資料。首先檢查該欄位是否為空。接下來轉換為位元組陣列。獲取位元組陣列并將其傳遞給 a 的建構式MemoryStream。流需要被處理，以便它在一個Using塊中。最后，可以將流分配給 的Image屬性PictureBox。

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim dt = GetDataFromSql()
    Dim BndSrc As New BindingSource()
    BndSrc.DataSource = dt
    ListBox1.DisplayMember = "ItemName"
    ListBox1.DataSource = BndSrc
    TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
    TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
    TextBox3.DataBindings.Add("Text", BndSrc, "Details")
End Sub

Private Function GetDataFromSql() As DataTable
    Dim dt As New DataTable
    Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
        cmd As New SqlCommand("select * FROM Items", connection)
        connection.Open()
        Using reader = cmd.ExecuteReader
            dt.Load(reader)
        End Using
    End Using
    Return dt
End Function

Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
    Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
    If row("Image") IsNot Nothing Then
        Dim b() As Byte = DirectCast(row("Image"), Byte()) '< ------ Cast the field to a Byte array.
        Using ms As New System.IO.MemoryStream(b)
            PictureBox1.Image = System.Drawing.Image.FromStream(ms)
        End Using
    Else
        PictureBox1.Image = Nothing
    End If
End Sub

編輯

我將代碼切換到可用于測驗的資料庫。即使它不是您的資料庫，我相信您將能夠遵循代碼。

這是我的資料庫的架構。

The main difference is I moved the DataTable to a class level variable so it can be seen from all methods. I changed the GetDataFromSql to a Sub. It adds the data to the class level DataTable (Bounddt). The AddItem method first gets the Byte() from a file. The row is added to the DataTable with an Object array with elements that match the DataTable.

Private Bounddt As New DataTable

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    GetDataFromSql()
    Dim BndSrc As New BindingSource()
    BndSrc.DataSource = Bounddt
    ListBox1.DisplayMember = "CustomerID"
    ListBox1.DataSource = BndSrc
    TextBox1.DataBindings.Add("Text", BndSrc, "CustomerID")
    TextBox2.DataBindings.Add("Text", BndSrc, "CustomerName")
End Sub

Private Sub GetDataFromSql() 
    Using connection As New SqlConnection("Data Source=****;Initial Catalog='Small Database';Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"),
    cmd As New SqlCommand("select * FROM Sales.Customer", connection)
        connection.Open()
        Using reader = cmd.ExecuteReader
            Bounddt.Load(reader)
        End Using
    End Using
    'Return dt
End Sub

Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
    Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
    If row("Picture") IsNot Nothing Then
        Dim b() As Byte = DirectCast(row("Picture"), Byte()) '< ------ Cast the field to a Byte array.
        Using ms As New System.IO.MemoryStream(b)
            PictureBox1.Image = System.Drawing.Image.FromStream(ms)
        End Using
    Else
        PictureBox1.Image = Nothing
    End If
End Sub
Private Sub AddItem()
    Dim picture = GetByteArr("C:\Users\maryo\OneDrive\Documents\Graphics\Animals\squirrel.png")
    Bounddt.Rows.Add({5, "George", 74, 62, "George", picture})
End Sub

Private Function GetByteArr(path As String) As Byte()
    Dim img = Image.FromFile(path)
    Dim arr As Byte()
    Dim imgFor As Imaging.ImageFormat
    Dim extension = path.Substring(path.LastIndexOf(".")   1)
    'There is a longer list of formats available in ImageFormat
    Select Case extension
        Case "png"
            imgFor = Imaging.ImageFormat.Png
        Case "jpg", "jpeg"
            imgFor = Imaging.ImageFormat.Jpeg
        Case "bmp"
            imgFor = Imaging.ImageFormat.Bmp
        Case Else
            MessageBox.Show("Not a valid image format")
            Return Nothing
    End Select
    Using ms As New MemoryStream
        img.Save(ms, imgFor)
        arr = ms.ToArray
    End Using
    Return arr
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    AddItem()
End Sub

uj5u.com熱心網友回復：

匯入 System.Data.SqlClient 匯入 System.IO 公共類 Form1

Dim con As SqlConnection
Dim cmd As SqlCommand
Dim rdr As SqlDataReader
Dim da As SqlDataAdapter
Private Const cs As String = "ConnectionString"

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    con = New SqlConnection(cs)
    con.Open()
    cmd = New SqlCommand("select * from [dbo].[Item_Details]", con)
    rdr = cmd.ExecuteReader()
    While rdr.Read
        ListBox1.Items.Add(rdr(1))
    End While
    con.Close()
End Sub

Private Sub ListBox1_MouseClick(sender As Object, e As MouseEventArgs) Handles ListBox1.MouseClick
    Try

        con = New SqlConnection(cs)
        con.Open()
        da = New SqlDataAdapter("Select *  from Item_Details where itemname='" & ListBox1.SelectedItem.ToString() & "'", con)
        Dim dt As New DataTable
        da.Fill(dt)
        For Each row As DataRow In dt.Rows
            TextBox1.Text = row(0).ToString()
            TextBox2.Text = row(1).ToString()
            TextBox3.Text = row(2).ToString()
            Dim data As Byte() = row(3)
            Dim ms As New MemoryStream(data)
            PictureBox1.Image = Image.FromStream(ms)
        Next

    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

結束類

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