原文 Storing and Retrieving Images from SQL Server using Microsoft .NET
Introduction
This article is about storing and retrieving images from database in Microsoft .NET using C#.
Tools Used
- SQL Server 2000
- Microsoft .NET Version 1.1
- C# (Windows Forms based application)
Storing Images
-
Create a table in a SQL Server 2000 database which has at least one field of type
IMAGE.Here is the script I used:
CREATE TABLE [dbo].[tblImgData] ( [ID] [ int ] NOT NULL , [Name] [ varchar ] ( 50 ) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [Picture] [ image ] NULL ) ON [ PRIMARY ] TEXTIMAGE_ON [ PRIMARY ] -
Actually
IMAGEfield is just holding the reference to the page containing the binary data so we have to convert our image into bytes.-
I used a file open dialog box to locate the file.
this .openFileDialog1.ShowDialog( this ); string strFn=this.openFileDialog1.FileName; -
By using
FileInfoclass, I retrieved the file size:FileInfo fiImage=new FileInfo(strFn); -
Declare an array of that size.
this .m_lImageFileLength=fiImage.Length; m_barrImg=new byte [Convert.ToInt32( this .m_lImageFileLength)]; -
By using
FileStreamobject, I filled the byte array.FileStream fs=new FileStream(strFn,FileMode.Open, FileAccess.Read,FileShare.Read); int iBytesRead=fs.Read(m_barrImg, 0 , Convert.ToInt32( this .m_lImageFileLength)); fs.Close();
Complete Load Image Code
protected void LoadImage() { try { this .openFileDialog1.ShowDialog( this ); string strFn=this.openFileDialog1.FileName; this .pictureBox1.Image=Image.FromFile(strFn); FileInfo fiImage=new FileInfo(strFn); this .m_lImageFileLength=fiImage.Length; FileStream fs=new FileStream(strFn,FileMode.Open, FileAccess.Read,FileShare.Read); m_barrImg=new byte [Convert.ToInt32( this .m_lImageFileLength)]; int iBytesRead = fs.Read(m_barrImg, 0 , Convert.ToInt32( this .m_lImageFileLength)); fs.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } -
I used a file open dialog box to locate the file.
-
Saving byte array data to database.
-
Create command text to insert record.
this .sqlCommand1.CommandText= " INSERT INTO tblImgData(ID,Name,Picture)" + " values(@ID,@Name,@Picture)" ; -
Create parameters.
this .sqlCommand1.Parameters.Add( " @ID" , System.Data.SqlDbType.Int, 4 ); this .sqlCommand1.Parameters.Add( " @Name" , System.Data.SqlDbType.VarChar, 50 ); this .sqlCommand1.Parameters.Add( " @Picture" , System.Data.SqlDbType.Image);Notice “
@Picture” has “SqlDbType.Image” because it is ofIMAGEtype Field. -
Provide the value to the parameters.
this .sqlCommand1.Parameters[ " @ID" ].Value=this.editID.Text; this .sqlCommand1.Parameters[ " @Name" ].Value=this.editName.Text; this .sqlCommand1.Parameters[ " @Picture" ].Value=this.m_barrImg;“
this .m_barrImg” is a byte array which we filled in the previous step. -
Now execute non-query for saving the record to the database.
int iresult=this.sqlCommand1.ExecuteNonQuery();
Complete Save Image Code
private void btnSave_Click( object sender, System.EventArgs e) { try { this .sqlConnection1.Open(); if (sqlCommand1.Parameters.Count ==0 ) { this .sqlCommand1.CommandText= " INSERT INTO tblImgData(ID," + " Name,Picture) values(@ID,@Name,@Picture)" ; this .sqlCommand1.Parameters.Add( " @ID" , System.Data.SqlDbType.Int, 4 ); this .sqlCommand1.Parameters.Add( " @Name" , System.Data.SqlDbType.VarChar, 50 ); this .sqlCommand1.Parameters.Add( " @Picture" , System.Data.SqlDbType.Image); } this .sqlCommand1.Parameters[ " @ID" ].Value=this.editID.Text; this .sqlCommand1.Parameters[ " @Name" ].Value=this.editName.Text; this .sqlCommand1.Parameters[ " @Picture" ].Value=this.m_barrImg; int iresult=this.sqlCommand1.ExecuteNonQuery(); MessageBox.Show(Convert.ToString(iresult)); } catch (Exception ex) { MessageBox.Show(ex.Message); } finally { this .sqlConnection1.Close(); } } -
Create command text to insert record.
Retrieving Image
Retrieving images from the database is the exact reverse process of saving images to the database.
-
First create command text to retrieve record.
SqlCommand cmdSelect = new SqlCommand( " select Picture" + " from tblImgData where ID=@ID" , this .sqlConnection1); -
Create parameter for the query.
cmdSelect.Parameters.Add( " @ID" ,SqlDbType.Int, 4 ); -
Provide value to the parameter.
cmdSelect.Parameters[ " @ID" ].Value=this.editID.Text; -
Open database connection and execute “
ExecuteScalar” because we want only “IMAGE” column data back.byte [] barrImg=( byte [])cmdSelect.ExecuteScalar();As the execute scalar returns data of “
Object” data type, we cast it tobytearray. -
Save this data to a temporary file.
string strfn=Convert.ToString(DateTime.Now.ToFileTime()); FileStream fs=new FileStream(strfn,FileMode.CreateNew,FileAccess.Write); fs.Write(barrImg, 0 ,barrImg.Length); fs.Flush(); fs.Close(); -
And display the image anywhere you want to display.
pictureBox1.Image=Image.FromFile(strfn);
Complete Image Retrieving Code
private
void
btnLoad_Click(
object
sender, System.EventArgs e)
{
try
{
SqlCommand cmdSelect=new SqlCommand(
"
select Picture"
+
"
from tblImgData where ID=@ID"
,
this
.sqlConnection1);
cmdSelect.Parameters.Add(
"
@ID"
,SqlDbType.Int,
4
);
cmdSelect.Parameters[
"
@ID"
].Value=this.editID.Text;
this
.sqlConnection1.Open();
byte
[] barrImg=(
byte
[])cmdSelect.ExecuteScalar();
string
strfn=Convert.ToString(DateTime.Now.ToFileTime());
FileStream fs=new FileStream(strfn,
FileMode.CreateNew, FileAccess.Write);
fs.Write(barrImg,
0
,barrImg.Length);
fs.Flush();
fs.Close();
pictureBox1.Image=Image.FromFile(strfn);
}
catch
(Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
this
.sqlConnection1.Close();
}
}
Bibliography
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Storing and Retrieving Images from SQL Server using Microsoft .NET
