Most of the web applications have a lot of images used in it. These images are usually stored in a web server folder and they are accessed by giving the relative path to the file with respect to the root folder of the website. .Net being the platform for distributed application now, ASP.Net can be used to store images that are small to be stored in a database like SQL Server 2000 and later versions. For this purpose the SQL Server database provides a data type called "image" which is used to store images in the database.
To access these images stored in the database we will be using the ADO.Net classes. To find out how to insert and retrieve an image in to the SQL Server database, you can create a .aspx page which can have a HTMLInputFile control which is used to select the image file that is to be saved in the database. You can also create a textbox control in which you can add the image name or some comment or an image id for the image saved. Use a button control to upload the image to the database. Namespaces like System.Data.SqlClient, System.Drawing, System.Data, System.IO, and System.Drawing.Imaging are used in this task.
In the OnClick property of the button you can write the following code to upload an image to the database.
// create a byte[] for the image file that is uploaded
int imagelen = Upload.PostedFile.ContentLength;
byte[] picbyte = new byte[imagelen];
Upload.PostedFile.InputStream.Read (picbyte, 0, imagelen);
// Insert the image and image id into the database
SqlConnection conn = new SqlConnection (@"give the connection string
here...");
try
{
conn.Open ();
SqlCommand cmd = new SqlCommand ("insert into ImageTable "
+ "(ImageField, ImageID) values (@pic, @imageid)",
conn);cmd.Parameters.Add ("@pic", picbyte);
cmd.Parameters.Add ("@imageid", lblImageID.Text);
cmd.ExecuteNonQuery ();
}
finally
{
conn.Close ();
}
You can also write the above code in a function and call that function in the OnClick event of the upload button. The code given above performs the following steps in the process of inserting an image into the database.
1. Get the content length of the image that is to be uploaded
2. Create a byte[] to store the image
3. Read the input stream of the posted file
4. Create a connection object
5. Open the connection object
6. Create a command object
7. Add parameters to the command object
8. Execute the sql command using the ExecuteNonQuery method of the command object
9. Close the connection object
To retrieve the image from the SQL Database you can perform the following steps.
1. Create a MemoryStream object. The code can be something like, MemoryStream mstream = new MemoryStream ();
2. Create a Connection object
3. Open the connection to the database
4. Create a command object to execute the command to retrieve the image
5. Use the command object's ExecuteScalar method to retrieve the image
6. Cast the output of the ExecuteScalar method to that of byte[] byte[] image = (byte[]) command.ExecuteScalar ();
7. Write the stream mstream.Write (image, 0, image.Length);
8. Create a bitmap object to hold the stream Bitmap bitmap = new Bitmap (stream);
9. Set the content type to "image/gif" Response.ContentType = "image/gif";
10. Use the Save method of the bitmap object to output the image to the OutputStream. bitmap.Save (Response.OutputStream, ImageFormat.Gif);
11. Close the connection
12. Close the stream mstream.Close();
Using the above steps you can retrieve and display the image from the database to the web page.
You can use these algorithms and take advantage of the "image" data type available in the SQLServer 2000 database to store small images that correspond to a particular record in the table of the database. This method of storing avoids the tedious task of tracking the path of the web folder if the images are stored in a web folder.
Visit a guide to .net for a complete introduction to .NET framework. Learn about ASP.NET, VB.NET, C# and other related technologies.
detailed home cleaning Lake Forest ..You use Ctrl+Alt+Del to see what's running on your PC,... Read More
Get started creating web pages using text files and HTML... Read More
If you are a building a website or a forum,... Read More
Saving Lives With A Pocket PCFree medical downloads can be... Read More
There have been some questions on anti-skip protection on mp3... Read More
I recently took a good look at what was keeping... Read More
Just The Facts, Ma'mPalm pilots are all the rage now.... Read More
Most people download and save so much information on their... Read More
We all enjoy our favorite screensavers but in the same... Read More
Feeling overwhelmed in selecting a new TV? With all the... Read More
Introduction In this article I will clearly spell out the... Read More
Here are some tips on how to use screensavers:First of... Read More
Google, in their march to stay ahead of the pack... Read More
I've worked my way from the CCNA to the CCIE,... Read More
Step 1:Open WinRAR and browse to the folder with your... Read More
1. Empty the Temp directory regularly. To do this, make... Read More
System File Checker is a great utility that is typically... Read More
In the 1950's and 1960's Polaroid's instant cameras were all... Read More
Addressing a D2X Digital SLRCoolpix 8800 search, this article provides... Read More
Lost & Found for the 21st CenturyIn today's hectic world... Read More
You don't have to fork out $250 for a super-diggy-whizbang... Read More
So you got yourself a digital camcorder. If you want... Read More
Cameras: still known for taking pictures but assumed as digital... Read More
After another security hole recently surfaced in Microsoft's Windows operating... Read More
Occupational Therapy Made EasierMedical downloads for the pda have improved... Read More
trusted cleaning company Des Plaines ..If you ask most people what frustrates them most about... Read More
First things first, what is Firefox? Well, it's a browser.... Read More
You will need the following:1. 1.44MB FDD (floppy)2. NVFLASH utility... Read More
Surf the 'Net for about 10 minutes and chances rate... Read More
It's free, it comes with Windows and it's used by... Read More
In this era of Internet, most people are frequent users... Read More
Computers are everywhere, and vary in specification, brands, sizes, shaped,... Read More
1. Empty the Temp directory regularly. To do this, make... Read More
I got my eyes set on a iPod mini, as... Read More
Passwords have a strange dual nature. The stronger and safer... Read More
I met an entrepreneur who hole heartedly disagree with an... Read More
Tip #1. Do a Google search. Don't be to general... Read More
Not sure what Windows registry is or how it works?... Read More
Tip #1 -- Rebates: A rebate is not always a... Read More
How familiar does the following sound? Your computer was working... Read More
About mail-mergingMail-merging is the process of merging variable data and... Read More
BIOS - Basic Input Output SystemThe central processing unit of... Read More
It seems like fast never quite rates fast enough.No matter... Read More
There are plenty of articles out there about how to... Read More
When you turn on your computer, does it act like... Read More
I recently took a good look at what was keeping... Read More
When studying for your Cisco CCNA, CCNP, or CCIE exam,... Read More
Having two operating systems is not as difficult as many... Read More
Good Morning Mr. Sampson. Please type in you Personal Identification... Read More
Viruses, software failures, power failures, human errors, hard drive failures... Read More
Personal Technology |