在数据库C＃中插入PDF [英] Insert PDF in database C#

问题描述

在数据库中插入PDF



这是好方法吗？



我有什么试过：

 private void Button2_Click（object sender，EventArgs e）//将pdf保存在数据库中
 {
 byte [] filedata = null; 
 MemoryStream ms = new MemoryStream（）; 
 filedata = ms.GetBuffer（）; 
 axAcroPDF1.src = LocalEncoding.GetString（ms.ToArray（））; 
 
 
 
使用（SqlConnection openCon = new SqlConnection（cs））
 {
 
 string saveStaff =declare @maxNo integer = 0从[dbo]中选择@maxNo = isnull（max（number），0）。[documents];设置@ maxNo = @ maxNo + 1; INSERT到dbo.documents（number，file_location，pdf_file）VALUES（@ maxNo，@ file_location ，@ pdf_file）; 
 
使用（SqlCommand querySaveStaff = new SqlCommand（saveStaff））
 {
 querySaveStaff.Connection = openCon; 
 
 querySaveStaff.Parameters.Add（@ file_location，SqlDbType.VarChar，255）.Value = file_locationTextBox.Text; 
 
 querySaveStaff.Parameters.AddWithValue（@ pdf_file，SqlDbType.VarBinary）.Value = filedata; 
 
 openCon.Open（）; 
 querySaveStaff.ExecuteNonQuery（）; 
 openCon.Close（）; 
 
 
} 
 
} 
 
} 

解决方案

虽然PDF字节数组的实际存储大致正确，但您的ID生成存在根本问题。不要自己手动添加ID，而是考虑将此字段更改为自动增量并让它自行处理。就目前而言，您冒着让两个字段尝试在多用户系统中添加相同ID的风险，因为无法保证您在下一个字段开始之前完成插入序列。

< blockquote>这段代码应该做什么？

  byte  [] filedata = 空;  //   filedata不包含任何内容 
 MemoryStream ms = 新 MemoryStream（）;  //  新的空内存流 
 filedata = ms.GetBuffer（）;  //   filedata仍然不包含任何内容 
 axAcroPDF1.src = LocalEncoding.GetString（ms.ToArray（ ））;  //  不知道应该做什么 
 
  //   ...  
 
 querySaveStaff.Parameters.AddWithValue（  @ pdf_file，SqlDbType.VarBinary）.Value = filedata; 
  //  但你永远不会向filedata添加任何内容，因此它会向数据库添加0x0。 

Insert PDF in database

Is this good way?

What I have tried:

private void Button2_Click(object sender, EventArgs e)   //Save pdf in database
        {
            byte[] filedata = null;
            MemoryStream ms = new MemoryStream();
            filedata = ms.GetBuffer();
            axAcroPDF1.src = LocalEncoding.GetString(ms.ToArray());



                    using (SqlConnection openCon = new SqlConnection(cs))
                    {

                        string saveStaff = "declare @maxNo integer = 0 select @maxNo = isnull(max(number), 0) from [dbo].[documents]; Set @maxNo=@maxNo+1; INSERT into dbo.documents (number,file_location, pdf_file) VALUES (@maxNo,@file_location,@pdf_file)";

                        using (SqlCommand querySaveStaff = new SqlCommand(saveStaff))
                        {
                            querySaveStaff.Connection = openCon;

                            querySaveStaff.Parameters.Add("@file_location", SqlDbType.VarChar, 255).Value = file_locationTextBox.Text;

                            querySaveStaff.Parameters.AddWithValue("@pdf_file", SqlDbType.VarBinary).Value = filedata;

                            openCon.Open();
                            querySaveStaff.ExecuteNonQuery();
                            openCon.Close();                            


                        }

                    }

}

解决方案

While the actual storing of the PDF byte array is roughly correct, you have a fundamental problem in your ID generation. Rather than manually adding an ID yourself, consider changing this field to an autoincrement and let that take care of itself. As it stands, you run the risk of having two fields attempt to add the same ID in a multi-user system because there's no guarantee that you will complete the insert sequence before the next one commences.

What is this code supposed to do?

            byte[] filedata = null;   // filedata contains nothing
            MemoryStream ms = new MemoryStream(); // a new empty memory stream
            filedata = ms.GetBuffer();  // filedata still contains nothing
            axAcroPDF1.src = LocalEncoding.GetString(ms.ToArray()); // no idea what this is supposed to do

// ...

querySaveStaff.Parameters.AddWithValue("@pdf_file", SqlDbType.VarBinary).Value = filedata;
// but you never add any content to filedata, so it adds 0x0 to the database.

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