由于某些原因,当我尝试为用户更新图像时,我的代码失败了。图像未正确保存。例如,38 kib的图像在数据库中保存为13个字节。
这是我的代码:
public void UploadImage(Image img)
{
OpenConnection();
MySqlCommand command = new MySqlCommand("", conn);
command.CommandText = "UPDATE User SET UserImage = '@UserImage' WHERE UserID = '" + UserID.globalUserID + "';";
byte[] data = imageToByte(img);
MySqlParameter blob = new MySqlParameter("@UserImage", MySqlDbType.Blob, data.Length);
blob.Value = data;
command.Parameters.Add(blob);
command.ExecuteNonQuery();
CloseConnection();
}
public byte[] imageToByte(Image img)
{
using (var ms = new MemoryStream())
{
img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
return ms.ToArray();
}
}
OpenConnection和closeconnection只是conn.Open()和conn.Close()。
有谁知道这里发生了什么?
答案 0 :(得分:2)
替换此代码:
OpenConnection();
MySqlCommand command = new MySqlCommand("", conn);
command.CommandText = "UPDATE User SET UserImage = '@UserImage' WHERE UserID = '" + UserID.globalUserID + "';";
byte[] data = imageToByte(img);
MySqlParameter blob = new MySqlParameter("@UserImage", MySqlDbType.Blob, data.Length);
blob.Value = data;
command.Parameters.Add(blob);
command.ExecuteNonQuery();
CloseConnection();
使用
var userImage = imageToByte(img);
OpenConnection();
var command = new MySqlCommand("", conn);
command.CommandText = "UPDATE User SET UserImage = @userImage WHERE UserID = @userId;";
var paramUserImage = new MySqlParameter("@userImage", MySqlDbType.Blob, userImage.Length);
var paramUserId = new MySqlParameter("@userId", MySqlDbType.VarChar, 256);
paramUserImage.Value = userImage;
paramUserId.Value = UserID.globalUserID;
command.Parameters.Add(paramUserImage);
command.Parameters.Add(paramUserId);
command.ExecuteNonQuery();
CloseConnection();
您发送的'@UserImage'
是一个10字节长的字符串,删除了引号,它应该可以正常工作。
上面的代码还使用了两个变量which you should always do的参数。
无论哪种方式希望这对你有帮助。