在图片框中设置图片从SQL数据库中检索

Question

This is my code to retrieve a image from sql database in C#. i want to set the image into a picturebox but im getting "system.drawing.dll parameter is not valid"

byte[] getImg;
     SqlConnection con2 = new SqlConnection(conString);
                con2.Open();
                if (con2.State == System.Data.ConnectionState.Open)
                {
                    string sss = "SELECT student_photo from student_reg where reg_year='" + year + "'and s_id='" +sid_lbl.Text+ "'";
                    SqlCommand cmd = new SqlCommand(sss, con2);
                    Console.WriteLine(sss);
                    SqlDataReader dr4 = cmd.ExecuteReader();

                    while (dr4.Read())
                    {



                        getImg = (byte[])(dr4["student_photo"]);






                    }
                    MemoryStream stream = new MemoryStream(getImg);
                    picturebox1.Image = Image.FromStream(stream);
    }
    con2.Close()

Answer 1

It's hard to pinpoint where your issue might be, but try a couple of changes:

1. Use parameters instead of hard-coding. In your example, the single quotes implied that id and reg_year were both strings. If this isn't the case, you want to strong-datatype your parameter values (convert to Int32 or whatever matches your database). Can you attach the DDL for the table?

2. If your output is one row / one column, consider ExecuteScalar .

If this doesn't work, my guess is that's not really an image file in the student_photo field.

Code:

SqlConnection con2 = new SqlConnection(conString);
con2.Open();

if (con2.State == System.Data.ConnectionState.Open)
{
    string sss = "SELECT student_photo from student_reg where reg_year=@YEAR and s_id=@ID";
    SqlCommand cmd = new SqlCommand(sss, con2);
    cmd.Parameters.AddWithValue("@YEAR", year);
    cmd.Parameters.AddWithValue("@ID", sid_lbl.Text);

    Byte[] getImg = (Byte[])cmd.ExecuteScalar();
    MemoryStream stream = new MemoryStream(getImg);
    Image img = Image.FromStream(stream);

    picturebox1.Image = img;
}
con2.Close()

Answer 2

Check the following Code:

string stuImg  = string.Empty;       
         SqlConnection con2 = new SqlConnection(conString);
            con2.Open();
            if (con2.State == System.Data.ConnectionState.Open)
            {
                string sss = "SELECT student_photo from student_reg where  reg_year='" + year + "'and s_id='" +sid_lbl.Text+ "'";
                SqlCommand cmd = new SqlCommand(sss, con2);
                Console.WriteLine(sss);
                SqlDataReader dr4 = cmd.ExecuteReader();
                while (dr4.Read())
                {
                    stuImg =dr4["student_photo"].ToString();
                }
                var pic = Convert.FromBase64String(stuImg);
                using (MemoryStream ms = new MemoryStream(pic))
                  {
                   picturebox1.Image = Image.FromStream(ms);
                  }
              }