How to insert NULL value to a variable of image datatype?

Question

I want to insert null value to the variable of image datatype and then update the column of image datatype in the Database

Dim PHOTO as Image = row("PHOTO")

Here, row("PHOTO") is fetched from a DataTable. If row("PHOTO") is Null, I want to insert the null value in PHOTO variable. I tried a lot but didn't succeed. Your help in this regard will be highly appreciated.

Yes, it didn't work. The error popups "Unable to insert null value in System.Web.UI.WebControls.Image" — Billing Systems
– Billing Systems, Commented Jun 14, 2016 at 9:53
Not so sure about vb.net, but shouldn't row("PHOTO") be equal to DBNull.Value and not to Nothing? — Zohar Peled
– Zohar Peled, Commented Jun 14, 2016 at 10:00
Used that one too. As its datatype is Image, so it is not accepting any other parameter/ value — Billing Systems
– Billing Systems, Commented Jun 14, 2016 at 10:05

Waqas · Accepted Answer · 2016-06-14 10:41:13Z

3

try following example,

If NOT IsDbNull(row("PHOTO")) Then
   //Do something
ELSE
   //your logic goes here
Dim PHOTO as Image=DBNull.Value;
End If

EDIT As you mentioned in comment, In C# my approach that works for me is...

 byte[] bimage = null;
if (txtPic.Text != "")
                {
                    string image = txtPic.Text;
                    Bitmap bmp = new Bitmap(image);
                    FileStream fs = new FileStream(image, FileMode.Open, FileAccess.Read);
                    bimage = new byte[fs.Length];
                    fs.Read(bimage, 0, Convert.ToInt32(fs.Length));
                    fs.Close();
                }

and now for stored procedure my image parameter will be as

if (bimage != null)
                    cmd.Parameters.AddWithValue("@imgdata", SqlDbType.Image).Value = bimage;
                else
                {
                    SqlParameter imageParameter = new SqlParameter("@imgdata", SqlDbType.Image);
                    imageParameter.Value = DBNull.Value;
                    cmd.Parameters.Add(imageParameter);
                }

edited Jun 14, 2016 at 10:41

answered Jun 14, 2016 at 10:27

Waqas

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2 Comments

Billing Systems Over a year ago

On declaring the variable, the error popups: Value of type 'System.DBNull' cannot be converted to 'System.Web.UI.WebControls.Image''

lionheart Over a year ago

This is because System.Web.UI.WebControls.Image can be used only with NULL value (and not with System.DBNull) when talking about nullable object.

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