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:

?Collapse|?Copy Code 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. ?Collapse|?Copy Code this.openFileDialog1.ShowDialog(this); string strFn=this.openFileDialog1.FileName;

By using?FileInfo?class, I retrieved the file size: ?Collapse|?Copy Code FileInfo fiImage=new FileInfo(strFn);

Declare an array of that size. ?Collapse|?Copy Code this.m_lImageFileLength=fiImage.Length; m_barrImg=new byte[Convert.ToInt32(this.m_lImageFileLength)];

By using?FileStream?object, I filled the byte array. ?Collapse|?Copy Code 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

?Collapse|?Copy 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);} }

Saving byte array data to database.

Create command text to insert record. ?Collapse|?Copy Code this.sqlCommand1.CommandText= "INSERT INTO tblImgData(ID,Name,Picture)" + " values(@ID,@Name,@Picture)";

Create parameters. ?Collapse|?Copy Code 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. ?Collapse|?Copy Code 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. ?Collapse|?Copy Code int iresult=this.sqlCommand1.ExecuteNonQuery();

Complete Save Image Code

?Collapse|?Copy 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();} }

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

Create parameter for the query. ?Collapse|?Copy Code cmdSelect.Parameters.Add("@ID",SqlDbType.Int,4);

Provide value to the parameter. ?Collapse|?Copy Code cmdSelect.Parameters["@ID"].Value=this.editID.Text;

Open database connection and execute “ExecuteScalar” because we want only “IMAGE” column data back. ?Collapse|?Copy Code 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. ?Collapse|?Copy Code 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. ?Collapse|?Copy Code pictureBox1.Image=Image.FromFile(strfn);

Complete Image Retrieving Code

?Collapse|?Copy 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

• Retrieving Images from SQL Server in ASP.NET
• Images, Thumbnails, SQL Server, and ASP.NET - Level 200

License

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posted on 2014-04-23 23:05 NET未來之路 閱讀(...) 評論(...) 編輯 收藏

轉載于:https://www.cnblogs.com/lonelyxmas/p/3684213.html

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