编程目的：文本框1中输入id号，则从openFileDialog中选择的图片会以二进制数据存进SQL数据库的对应表的id列；文本框2中输入姓名，从数据库读取对应name的照片并显示在pictureBox控件上。

预备操作：新建一个sql数据库，包含一个拥有id和name，image的表，如下图所示，窗体中拖拽两个文本框和两个button按钮。

1、主功能类

  public void SaveImage(string ID,OpenFileDialog openF)  //openFileDialog打开的图片以二进制流的方式存到数据库的指定表的指定id号的记录中
        { 
            string P_str = openF.FileName;
            FileStream fs = new FileStream(P_str,FileMode.Open,FileAccess.Read);
            BinaryReader br = new BinaryReader(fs);
            byte[] imageBytesIn = br.ReadBytes((int)fs.Length);
            SqlConnection conn = BaseClass.DBConn.CyCon();
            conn.Open();
            StringBuilder strSql = new StringBuilder();
            strSql.Append("update test_photo set photo=@Photo where id="+ID);
            SqlCommand cmd = new SqlCommand(strSql.ToString(),conn);
            cmd.Parameters.Add("@Photo",SqlDbType.Binary).Value=imageBytesIn;
            cmd.ExecuteNonQuery();
            conn.Close();
        }

        public void Get_Image(string  yname,PictureBox pb)//从数据库中读取指定姓名的二进制数据图片并显示
        {   byte[]imagebytes=null;
            SqlConnection conn = BaseClass.DBConn.CyCon();
            conn.Open();
            SqlCommand com=new SqlCommand("select * from test_photo where name='"+yname+"'",conn);
            SqlDataReader dr=com.ExecuteReader();
            while(dr.Read())
            {imagebytes=(byte[])dr.GetValue(1);}
            dr.Close();
            conn.Close();
            MemoryStream ms=new MemoryStream(imagebytes);
            Bitmap bmpt = new Bitmap(ms);
            pb.Image = bmpt;
          
        }

  bll b = new bll();
        
        private void btnSavePhotoToDB_Click(object sender, EventArgs e)
        {
            
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                b.SaveImage(textBox1.Text, openFileDialog1);
                
            }
            
            MessageBox.Show("存照片成功");//支持bmp，jpg，gif
        }

        private void btnShowPhotoFromDB_Click(object sender, EventArgs e)
        {
            b.Get_Image(textBox2.Text, pictureBox1);
        }