Storing and Retrieving Images from SQL Server using Microsoft .NET

原文 Storing and Retrieving Images from SQL Server using Microsoft .NET

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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:

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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 IMAGE field 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.

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this.openFileDialog1.ShowDialog(this);
string strFn=this.openFileDialog1.FileName;

By using FileInfo class, I retrieved the file size:
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```
FileInfo fiImage=new FileInfo(strFn);
```

Declare an array of that size.

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this.m_lImageFileLength=fiImage.Length;
m_barrImg=new byte[Convert.ToInt32(this.m_lImageFileLength)];

By using FileStream object, I filled the byte array.

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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

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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);
    }
}

Saving byte array data to database.

Create command text to insert record.

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this.sqlCommand1.CommandText=
  "INSERT INTO tblImgData(ID,Name,Picture)" +
  " values(@ID,@Name,@Picture)";

Create parameters.

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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 of IMAGE type Field.

Provide the value to the parameters.

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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.
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```
int iresult=this.sqlCommand1.ExecuteNonQuery();
```

Complete Save Image Code

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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();
    }
}

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.

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SqlCommand cmdSelect = new SqlCommand("select Picture" +
                       " from tblImgData where ID=@ID",
                       this.sqlConnection1);

Create parameter for the query.
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```
cmdSelect.Parameters.Add("@ID",SqlDbType.Int,4);
```

Provide value to the parameter.

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cmdSelect.Parameters["@ID"].Value=this.editID.Text;

Open database connection and execute “ExecuteScalar” because we want only “IMAGE” column data back.
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```
byte[] barrImg=(byte[])cmdSelect.ExecuteScalar();
```
As the execute scalar returns data of “Object” data type, we cast it to byte array.

Save this data to a temporary file.

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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.
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```
pictureBox1.Image=Image.FromFile(strfn);
```

Complete Image Retrieving Code

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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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