如何在图片框中显示来自访问数据库的附件图像

Question

我正在尝试在图片框中显示来自数据库附件的图像，但在

上出现错误

ImageByte = (byte[]) vcom.ExecuteScalar();

它说

Unable to cast object of type 'System.String' to type 'System.Byte[]'.

这是我的代码

byte[] ImageByte = null;
MemoryStream MemStream = null;

OleDbConnection cn = new OleDbConnection();
cn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:/ALL/Database7.accdb";
cn.Open();

OleDbCommand command = new OleDbCommand();
command.Connection = cn;
string sql = "select Attachments from Contacts where ID = 1";
OleDbCommand vcom = new OleDbCommand(sql, cn);

ImageByte = (byte[]) vcom.ExecuteScalar();

MemStream = new MemoryStream(ImageByte);
pictureBox1.Image = Image.FromStream(MemStream);
cn.Close();

Answer 1

在 MSAccess 中，附件二进制数据位于附件字段的子元素中。

这将 return 一个 byte[]。这个 byte[] 由 MSAccess 填充，前 20 个字节包含 MetaData。

您可以使用 Linq .Skip() 删除前 20 个字节

string sql = "select Attachments.FileData from Contacts where ID = 1";
OleDbCommand vcom = new OleDbCommand(sql, cn);

byte[] ImageByte = (byte[]) vcom.ExecuteScalar(); //contains 20 extra bytes

MemoryStream MemStream = new MemoryStream(ImageByte.Skip(20).ToArray()); //Read bytes starting at position 20

Image image = Image.FromStream(MemStream); //Will work now
pictureBox1.Image = image;
...

这个有用吗？

如何在图片框中显示来自访问数据库的附件图像

How to Display attachments image from access db in picturebox

c#

oledb