How to I retreive a pdf file that is saved as binary data in the database and view that file in web controls using VB.NET

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i have tried this code but it dosent work can anyone help me with this code

What I have tried:

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



       myconnection = New SqlConnection("SELECT Data FROM [pdf] WHERE id = " & TextBox1.Text & "")


       Using con As New SqlConnection("Data Source=(localdb)\Projects;Initial Catalog=pdf;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False")
           con.Open()
           Using com As New SqlCommand("SELECT Data FROM [pdf] WHERE id = " & TextBox1.Text & "", con)
               Using reader As SqlDataReader = com.ExecuteReader()
                   While reader.Read()
                       Dim fileData As Byte() = DirectCast(reader("Data"), Byte())

                   End While
               End Using
           End Using
       End Using



       WebBrowser1.Navigate(filedata)
   End Sub

Posted 27-Oct-20 16:57pm

Rahul Chand

Updated 27-Oct-20 19:15pm

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Comments

Richard Deeming 29-Oct-20 13:43pm

Using com As New SqlCommand("SELECT Data FROM [pdf] WHERE id = " & TextBox1.Text & "", con)

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

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Sandeep Mewara · Answer 1 · 2020-10-27T19:16:00

You have not shared any issue with your code (does not work gives no clue to us on what issue you are facing). Looking at your code, I don't see where you define the ContentType of the binary data when you retrieve.

Refer the following article for it: Convert Binary data to PDF file in C# and VB.Net[^]

VB.NET code snippet:

VB

Using con As New SqlConnection(constr)
    Using cmd As New SqlCommand()
        cmd.CommandText = "SELECT Name, Data, ContentType FROM tblFiles WHERE Id=@Id"
        cmd.Parameters.AddWithValue("@Id", id)
        cmd.Connection = con
        con.Open()
        Using sdr As SqlDataReader = cmd.ExecuteReader()
            sdr.Read()
            bytes = DirectCast(sdr("Data"), Byte())
            contentType = sdr("ContentType").ToString()
            fileName = sdr("Name").ToString()
        End Using
        con.Close()
    End Using
End Using

Try out.