c#从mysql检索保存的图像时出现错误

本文关键字：错误 图像 mysql 检索 保存 | 更新日期: 2023-09-27 18:14:02

我已经在表中创建了图像列mediumblob

保存图像，我使用以下代码

byte[] ImageData;
fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
ImageData = new byte[Convert.ToInt32(fs.Length)];
fs.Read(ImageData, 0, Convert.ToInt32(fs.Length));
fs.Close();
string qry = "Update admin_info set `img`='"+ ImageData + "' where id='AD001";
using (con = new MySqlConnection(DBConStr))
{
    con.Open();
    using (cmd = new MySqlCommand(qry, con))
    {
         cmd.ExecuteNonQuery();
    }
}
    MessageBox.Show(" Profile Picture Updated Successfully!", "Success!", MessageBoxButtons.OK, MessageBoxIcon.Information);

，它是成功的，但我得到参数无效，而检索它到图片框使用下面的代码

using (MySqlConnection conn = new MySqlConnection("Server = localhost; Port = 3307; database = attendance; uid = root; pwd = MJN45720!"))
{
     conn.Open();
     string myQuery = "SELECT img FROM admin_info where id='AD001'";
     using (MySqlCommand cmd = new MySqlCommand(myQuery, conn))
     {
         using (var reader = cmd.ExecuteReader())
         {
              while (reader.Read())
              {
                   byte[] x = (byte[])reader["img"];
                   MemoryStream ms = new MemoryStream(x);
                   pictureBox1.Image = new Bitmap(ms); //Parameter invalid in this line
               }
         }
     }

搜索了许多论坛，厌倦了他们在每个帖子中的建议，但我无法解决…

c#从mysql检索保存的图像时出现错误

您没有正确地将图像保存到DB。string qry = "Update admin_info set ``img``='"+ ImageData + "' where id='AD001";线将导致qry = "Update admin_info set ``img``='System.Byte[]' where id='AD001，因为你正在转换字节数组到字符串，这将导致类型名称。您必须将字节数组转换为十六进制字符串，这应该被SQL引擎接受。

        byte[] ImageData;
        fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
        br = new BinaryReader(fs);
        ImageData = br.ReadBytes((int)fs.Length);
        br.Close();
        fs.Close();
       using (con = new MySqlConnection(DBConStr))
        {
            con.Open();
            using (cmd = new MySqlCommand(qry, con))
            {
                cmd.Parameters.Add("@pimage", MySqlDbType.Blob);
                cmd.Parameters["@pimage"].Value = ImageData;
                cmd.ExecuteNonQuery();
            }
        }

这解决了我的问题，我也能检索…感谢Honz指出将其转换为sting的实际问题:)

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