The Code Project - Uploading / Downloading Pictures to / from a SQL Server - C# DatabaseView our advertisersAdvertise with us ASP.NET, All Topics, C#, .NET >> C# Database >> General Uploading / Downloading Pictures to / from a SQL Server By Alexandru Ghiondea Describes how to upload and download pictures to and from a SQL Server database. C#, SQL Windows (WinXP), .NET (.NET 1.1) Win32, SQL (SQL 2000), VS (VS.NET2003) DB, Dev Posted 29 Oct 2004 4:49 Articles by this author 18,413 views Search: Articles Authors Help!ArticlesMessage BoardsStoreFrontLounge Toolbox Broken Article? VS.NET 2003 for $899 Ultimate Toolbox $499 Print version Send to a friend Sign in / Sign up Email Password Remember me Lost your Password? 15 members have rated this article. Result: Popularity: 5.33. Rating: 4.53 out of 5. Download demo project - 19 Kb Download database script - 0.7 Kb Introduction In order to provide your application with cool pictures, you can employ two techniques (at least). One of them is that you can save the pictures in a folder and store the path to each one in a database or file. The other one is to store the entire file into a database, along with its file name. Each of them has its ups and downs: If you save your files to a folder, you might accidentally delete a file from that folder. If this happens, you will end up with a broken link in your database or configuration file. However, the hard disk storage space is cheap, so you can afford to store a lot of files. If you store your files into a database, you can enforce security by using the security settings of the database. Also, there are no broken links ever. However, the database storage space is more expensive. Another idea is that you can save a thumbnail of the image on the database for quick access and save the actual picture on hard drive. Of course, each application has its particularities, and you have to choose which one you will use. OK. Enough of the philosophical talk! Lets dive into the good stuff. The application The problem of uploading files to a database is not that difficult. You have to use, on the server, a certain data type when creating the table. This data type has to be capable of storing large amounts of binary data. When using Microsoft SQL Server, this data type is called image. For more information, see BLOB (Binary Large OBject) for a short definition, and Books Online for a complete reference. The client has to obtain the data from the file in binary format a byte array and call a procedure on the server with that array as a parameter. The SQL Server procedures In this presentation, I assume that I have a database Pictures on the server with a table called Pictures. The structure of this table is as follows: Field NameField Type kFileNameLong PictureImage FileNameVarchar(250) I also have stored procedures for uploading, downloading, and retrieving the list of uploaded files. These are shown below. For uploading a file: UploadFile:CREATE PROCEDURE [dbo].[UploadFile]( @Picture image, @FileName varchar(250), @kFileName bigint output)ASinsert into Pictures(Picture, FileName) values (@Picture,@FileName)select @kFileName = SCOPE_IDENTITY()GOFor downloading a file: DownloadFile:CREATE PROCEDURE [dbo].[DownloadFile]( @kFileName bigint, @FileName varchar(250) output)ASselect Picture, FileName from Pictures where kFileName=@kFileNameGOFor retrieving the list of uploaded files: getUploadedFiles:CREATE PROCEDURE [dbo].[getUploadedFiles]ASSelect ltrim(str(kFileName)) + " - " + FileName as Name from PicturesGOThe C# Class - with commentsusing System;using System.IO;using System.Data;using System.Text;using System.Data.SqlClient;/* * Autor: Ghiondea Alexandru * Date: 08 october 2004 * Description: Implements methods for uploading and downloading files * with MS SQL Server * */namespace PicturesInSQLServer{ /// /// This class manages uploads and downloads to and from an SQL Server /// public class TransferPictures { /// /// Gets from the server a list of uploaded files into a dataSet /// /// The dataset /// The table in the dataset public void GetUploadedFiles(ref DataSet ds, string table) { // // The variables required for connecting to the server. // SqlConnection conn =null; SqlCommand cmd = null; SqlDataAdapter da = null; // ---------------------------------------------- try { // // If the table already exists, cleares its content. Else adds a new table. // if (ds.Tables.Contains(table)) ds.Tables[table].Clear(); else ds.Tables.Add(table); // ---------------------------------------------- // // Creates a connection to the database and initilizes the command // conn = new SqlConnection(ConnectionString()); cmd = new SqlCommand("getUploadedFiles",conn); cmd.CommandType = CommandType.StoredProcedure; // ---------------------------------------------- // // Initializes the DataAdapter used for retrieving the data // da = new SqlDataAdapter(cmd); // ---------------------------------------------- // // Opens the connection and populates the dataset // conn.Open(); da.Fill(ds,table); conn.Close(); // ---------------------------------------------- } catch(Exception e) { // // If an error occurs, we assign null to the result // and display the error to the user, // with information about the StackTrace for debugging purposes. // Console.WriteLine(e.Message + " - " + e.StackTrace); } } /// /// Uploads a file to the database server. /// /// The filename of the picture to be uploaded /// The id of the file on the server. public long UploadFile(string FileName) { if (!File.Exists(FileName)) { return -1; } FileStream fs=null; try { #region Reading file fs = new FileStream(FileName,FileMode.Open); // // Finding out the size of the file to be uploaded // FileInfo fi = new FileInfo(FileName); long temp = fi.Length; int lung = Convert.ToInt32(temp); // ------------------------------------------ // // Reading the content of the file into an array of bytes. // byte[] picture=new byte[lung]; fs.Read(picture,0,lung); fs.Close(); // ------------------------------------------ #endregion long result = uploadFileToDatabase(picture,fi.Name); return result; } catch(Exception e) { Console.WriteLine(e.Message + " - " + e.StackTrace); return -1; } } /// /// Wrapper for downloading a file from a database. /// /// The Unique ID of the file in database /// The file name as it was stored /// in the database. /// The byte array required OR null if the ID is not found public byte[] DownloadFile(long kFileName, ref string fileName) { byte[] result = downloadFileFromDatabase(kFileName, ref fileName); return result; } /// /// Returns the connection string for connecting to the database /// /// The Connection string. public static string ConnectionString() { // // We consider that the database is situated // on the same computer that runs the program. // To connect to a remote server, replace 'Data Source' // with the name of that server. // return "Connect Timeout=600;Integrated Security=SSPI;" + "Persist Security Info=False;Initial Catalog=Pictures;" + "Packet Size=4096;Data Source=" + System.Environment.MachineName.Trim(); } /// /// Uploades a file to an SQL Server. /// /// A byte array that contains /// the information to be uploaded. /// The file name asociated /// with that byte array. /// The unique ID of the file on the server /// OR -1 if an error occurs. private long uploadFileToDatabase(byte[] picture, string fileName) { // // Defining the variables required for accesing the database server. // SqlConnection conn = null; SqlCommand cmd =null; SqlParameter kFileName =null; SqlParameter FileName =null; SqlParameter pic =null; // By default, we assume we have an error. If we succed in uploading // the file, we'll change this // to the unique id of the file long result=-1; try { // // Connecting to database. // conn = new SqlConnection(ConnectionString()); cmd = new SqlCommand("UploadFile",conn); // We assume there is a stored procedure called UploadFile cmd.CommandType = System.Data.CommandType.StoredProcedure; // ---------------------------------------------- // // Initializing parameters and assigning // the values to be sent to the server // kFileName = new SqlParameter("@kFileName", System.Data.SqlDbType.BigInt,8); kFileName.Direction = ParameterDirection.Output; // This parameter does not have a size because // we do not know what the size is going to be. pic = new SqlParameter("@picture",SqlDbType.Image); pic.Value = picture; FileName = new SqlParameter("@FileName",SqlDbType.VarChar,250); FileName.Value = fileName; // ---------------------------------------------- // // Adding the parameters to the database. // Remember that the order in which the parameters // are added is VERY important! // cmd.Parameters.Add(pic); cmd.Parameters.Add(FileName); cmd.Parameters.Add(kFileName); // ---------------------------------------------- // // Opening the connection and executing the command. // conn.Open(); cmd.ExecuteNonQuery(); conn.Close(); // ---------------------------------------------- // // The result is the unique identifier created on the database. // result = (long)kFileName.Value; // ---------------------------------------------- // // Disposing of the objects so we don't occupy memory. // conn.Dispose(); cmd.Dispose(); // ---------------------------------------------- } catch(Exception e) { // // If an error occurs, we report it to the user, // with StackTrace for debugging purposes // Console.WriteLine(e.Message + " - " + e.StackTrace); result = -1; // ---------------------------------------------- } return result; } /// /// Downloades a file from a database according // to the unique id in that database. /// /// The ID of the file in the database /// The filename of the file /// as it was stored in the database. /// A byte array containing /// the information required. private byte[] downloadFileFromDatabase(long kFile, ref string FileName) { SqlConnection conn =null; SqlCommand cmd = null; SqlParameter kFileName = null; SqlParameter fileName = null; SqlDataReader dr=null; byte[] result=null; try { // // Connecting to database. // conn = new SqlConnection(ConnectionString()); cmd = new SqlCommand("DownloadFile",conn); cmd.CommandType = System.Data.CommandType.StoredProcedure; // ---------------------------------------------- // // Initializing parameters and assigning the values to be sent to the server // kFileName= new SqlParameter("@kFileName",System.Data.SqlDbType.BigInt,8); kFileName.Value = kFile; fileName = new SqlParameter("@FileName",SqlDbType.VarChar,250); fileName.Direction = ParameterDirection.Output; // ---------------------------------------------- // // Adding the parameters to the database. // Remember that the order in which the parameters // are added is VERY important! // cmd.Parameters.Add(kFileName); cmd.Parameters.Add(fileName); // ---------------------------------------------- // // Opening the connection and executing the command. // The idea behind using a dataReader is that, // on the SQL Server, we cannot assign to a // variable the value of an image field. // So, we use a querry to select the record we want // and we use a datareader to read that query. // Because we are returnig information based // on a primary key, we are always returning // only one row of data. // conn.Open(); dr = cmd.ExecuteReader(); dr.Read(); // // We are casting the value returned // by the datareader to the byte[] data type. // result = (byte[])dr.GetValue(0); // // We are also returning the filename associated with the byte array. // FileName = (string)dr.GetValue(1); // // Closing the datareader and the connection // dr.Close(); conn.Close(); // ------------------------------------------ // // Disposing of the objects so we don't occupy memory. // conn.Dispose(); cmd.Dispose(); // ------------------------------------------ } catch(Exception e) { // // If an error occurs, we assign null // to the result and display the error to the user, // with information about the StackTrace for debugging purposes. // Console.WriteLine(e.Message + " - " + e.StackTrace); result = null; } return result; } }}A sample application I have also written a small application to demonstrate how to use these methods. A screenshot of it is shown below: The application uploads a file to the server and displays a list of files on the server. When double-click-ing on the filename in the list, the file is downloaded and displayed in the picture box. Below are some snippets of relevant code:private void UploadedFiles_DoubleClick(object sender, System.EventArgs e) { // // Finds the unique id of the file. // DataRowView drv = (DataRowView) UploadedFiles.SelectedItem; string selectedText = drv.Row["Name"].ToString(); long id=-1; id = long.Parse(selectedText.Substring(0,selectedText.IndexOf(" - ",0)).Trim()); string filename=null; TransferPictures up = new TransferPictures(); byte[] result = up.DownloadFile(id,ref filename); up = null; try { // // We cannot assign a byte array directly to an image. // We use MemoryStream, an object that creates a file in memory // and than we pass this to create the image object. // MemoryStream ms= new MemoryStream(result,0,result.Length); Image im = Image.FromStream(ms); Picture.Image = im; } catch(Exception ee) { MessageBox.Show("An error has occured.\n" + ee.Message); } } private void UploadFile_Click(object sender, System.EventArgs e) { // // Gets the file to be uploaded // OpenFileDialog ofd = new OpenFileDialog(); ofd.ShowDialog(); if (ofd.FileName=="" || !File.Exists(ofd.FileName)) { // // If the requested file is not ok... // return; } TransferPictures up = new TransferPictures(); long id =up.UploadFile(ofd.FileName); string msg=null; if (id >0) { msg = "Upload succesful"; LoadInformationFromDataBase(); } else { msg = "An error has occured"; } MessageBox.Show(msg); } private void LoadInformationFromDataBase() { TransferPictures up = new TransferPictures(); up.GetUploadedFiles(ref ds,"Pictures"); UploadedFiles.DataSource = ds.Tables["Pictures"]; UploadedFiles.DisplayMember = "Name"; } private void frmMain_Load(object sender, System.EventArgs e) { LoadInformationFromDataBase(); }Conclusion Well, choosing which type of image file storage technique to use is up to the person designing a specific application. I have tried here to show you how you can store them in a database. Happy coding! Bibliography Books Online MSDN About Alexandru Ghiondea Student at the Computer Science Faculty in Bucharest Click here to view Alexandru Ghiondea's online profile. Other popular articles: QueryCommander SQL Editor QueryCommander SQL editor with IntelliSense, wrapped in a Visual Studio type of environment. QueryCommander supports: Microsoft SQL Server 6.5-2005, MySQL 4.*-5.1, and Oracle 9i. SQL Injection Attacks and Some Tips on How to Prevent Them Discusses various aspects of SQL Injection attacks, what to look for in your code, and how to secure it against SQL Injection attacks. SQL Server DO's and DONT's SQL Server database best practices Inserting relational data using DataSet and DataAdapter This article describes the process of inserting data in a DataSet and then submitting this changes to the database. It targets the issue when having IDENTITY/AutoNumber columns in the database. [Top]Sign in to vote for this article: PoorExcellent Premium Sponsor FAQ Noise level Very High High Medium Low Very low Search comments View Normal (slow) Preview (slow) Message View Topic View Thread View Expanded (Supporters only) Per page 10 25 50 (must logon) New threadMsgs 1 to 12 of 12 (Total: 12) (Refresh)First Prev Next Subject Author Date a problem with the code Shanyok 8:59 5 Mar '05 Hi Alex Good example!! I got exception at this line - "id = long.Parse(selectedText.Substring(0,selectedText.IndexOf(" - ",0)).Trim());" An unhandled exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll Additional information: Length cannot be less than zero. I didn't change the code..this is what so weird here.... do u have any idea what is the problem might be ? [Reply][Email][View Thread][Get Link][Modify|Delete] Re: a problem with the code Alexandru Ghiondea 14:30 5 Mar '05 Hello and Thank you for your appreciation. First of all I would like to ask you a few questions about how did that error occured. I mean what did you do to get that error. Secondly, the line of code does a simple thing. It separates the id of the file in the database from the filename used to upload it. So, if you have an entry like 1 - somePicture.bmp the code will extract the portion from the beginning of the string to the - character (i.e. 1), and it will try to convert that string to a long in order to request the file with that id from the server. Anyway, please provide some extra information about what do you do to get that error and I will try to answer it. [Reply][Email][View Thread][Get Link][Modify|Delete] Score: 2.0 (1 vote). Re: a problem with the code Shanyok 15:21 5 Mar '05 Hi Alex Thank you for your response ok...I found the problem... the id-file_name were shown in the listview in different order. "1 -somePicture.bmp" instead of "1 - somePicture.bmp" . there wasn't white space between "-" and the "file_name". so after I changed the code to : id = long.Parse(selectedText.Substring(0,selectedText.IndexOf(" -",0)).Trim()); it started working perfectly. I looked at the SP but it looks fine CREATE PROCEDURE [dbo].[getUploadedFiles] AS select ltrim(str(kFileName)) + " - " + FileName as Name from Pictures GO so I don't know yet why all the items in the Uploadedfiles listview are presented without the white space between "-" and "filename" [Reply][Email][View Thread][Get Link][Modify|Delete] Re: a problem with the code Alexandru Ghiondea 15:46 5 Mar '05 I'm glad you got it to work. I can't imagine why it wouldn't work. I will think about that an if I find an answer, I'll let you know. Try to download it again from the site. See if it works. But, since you got it to work, I don't see the point. Happy coding! [Reply][Email][View Thread][Get Link][Modify|Delete] To save all types of file in Sql Server alijhon 9:22 4 Feb '05 hi!, Very Good article, My requirment is to upload all types of files to a Microsoft Sql Server 2000 and download them to modify through an ASP.net. do i have to use image data type for saving all types of documents. pls provide some help, thank you, ~ALI~ [Reply][Email][View Thread][Get Link][Modify|Delete] Re: To save all types of file in Sql Server Alexandru Ghiondea 3:24 7 Feb '05 Hello. Thank you for your apreciation. The answer to your question is YES. For any type of files, you have to use the Image datatype. The reason for doing that is that, in SQL Server, the Image datatype is used as a BLOB field. So, you can upload any stream of bytes into an Image field. Hope this helps and, for other questions, don't hesitate. Alex. [Reply][Email][View Thread][Get Link][Modify|Delete] To upload all file types through ASP.net manoyaka 3:58 30 Dec '04 hi!, thanks for your article, My requirment is to upload all types of files to a database and download them to modify through an ASP.net. pls provide some help, thank you, mano [Reply][Email][View Thread][Get Link][Modify|Delete] Re: To upload all file types through ASP.net Alexandru Ghiondea 7:04 8 Jan '05 Hello and thank you for your message. If I understand correctly you want to store any type of file in your SQL Server. Well, as I wrote in the article, you can do that just fine using the code I presented. I chose to focus the application on images because I needed pictures in an application I wrote. So, you can use this program for any type of files!!! About processing them with ASP.NET, can you be more clear about what you want to do? Best Regards, Alexandru Ghiondea [Reply][Email][View Thread][Get Link][Modify|Delete] is it recomended? Jordi Corominas 6:14 25 Nov '04 Hi! I'm interested in storinc pictures or word documents for an application i'm developping but i'm not sure if this is the best way to do it. I have been trying to store the pictures to the server (in a folder) and store at the DB the path of the picture. What do you think is better to store the entire pic to the DB or my way of storing only the path? Thanks! Jordi "Catalonia is not Spain" [Reply][Email][View Thread][Get Link][Modify|Delete] Re: is it recomended? Alexandru Ghiondea 9:49 25 Nov '04 Hi. In the application I used pictures, but the code I presented allows you to upload any type of file. Anyway. To answer your question like my teachers did: It all depends . I can give you some ideas to think about: 1. If you store the pictures in the database, without your application it can be rather difficult to acces it. If you store it in a file, you don't have this problem. 2. It depends on the size of the pictures. If you store them in a database, you will have to download them before doing anything, and this may cause slow response in your application. 3. If you have a lot of small files, it will be difficult for you to acces the required one manually, especially when the file names are filenamexxx. 4. If security is an issue, you might consider the database because, with a database you have the database system as another security mechanism. I hope that what I said will help you decide. If you need further help, don't hesitate to email me. Sincerely, Alexandru Ghiondea [Reply][Email][View Thread][Get Link][Modify|Delete] @@IDENTITY bug jlb 14:15 2 Nov '04 I noticed you were using @@IDENTITY to retrieve the identity of the row in the picture column. This really should be a call to SCOPE_IDENTITY() instead just in case some future trigger on this table (for auditing perhaps) inserts its own row. HTH. Regards, John B. [Reply][Email][View Thread][Get Link][Modify|Delete] Score: 5.0 (1 vote). Re: @@IDENTITY bug Alexandru Ghiondea 3:46 3 Nov '04 You are correct, and I changed my code to obtain the @@IDENTITY usint Scope_Identity. I didn't think about this type of problem when I originally wrote the article. Thank you for interest and observation, Alex G. [Reply][Email][View Thread][Get Link][Modify|Delete] Last Visit: 11:53 Wednesday 13th April, 2005First Prev Next ASP.NET, All Topics, C#, .NET >> C# Database >> General Updated: 29 Oct 2004 4:49 Article content copyright Alexandru Ghiondea, 2004 everything else Copyright CodeProject, 1999-2005. 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