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using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Data.SqlClient;

using System.Drawing;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace 读取数据库中的图片

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        /// <summary>

        /// 选择图片

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void button1_Click(object sender, EventArgs e)

        {

            //初始化打开文件 对话框

            OpenFileDialog ofdlgTest = new OpenFileDialog();

            ofdlgTest.Filter = "*.jpg|*.png";   //文件过滤 筛选可以打开的文件

            ofdlgTest.Multiselect = false;    //设置不可以选择多个文件

            //显示文件打开对话框

            DialogResult result = ofdlgTest.ShowDialog();

            //选择打开按钮的时候，将文件名显示到文本框中

            if (result== DialogResult.OK)                   //判断是否打开文件

            {

                this.textBox1.Text = ofdlgTest.FileName;

                pictureBox1.Image = Image.FromFile(ofdlgTest.FileName);

            }

        }

        /// <summary>

        /// 存入数据库

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void button2_Click(object sender, EventArgs e)

        {

            string constr = "Data Source=.;Initial Catalog=MyFirstDatabase;User Id=sa;PassWord=91811372c";

            using(SqlConnection con=new SqlConnection(constr))

            {

                //sql语句  插入图片

                string sql = "insert into ImageTest values(@UserImage)";

                using(SqlCommand com=new SqlCommand(sql,con))

                {

                    byte[] buffer;   //将图片转换为字节数组 存入数据库   textBox1.Text 是文件的路径

                    using(FileStream stream = new FileStream(textBox1.Text, FileMode.OpenOrCreate, FileAccess.Read))

                    {

                        //通过文件路径 打开文件

                        buffer = new byte[stream.Length];

                        stream.Read(buffer, 0, buffer.Length);  //转换后 ，存入buffer中

                    }

                    //这个参数 其实 也没必要声明 不过习惯使用 带参数的sql语句了

                    SqlParameter pms = new SqlParameter("@UserImage", SqlDbType.Image) { Value = buffer };

                    com.Parameters.Add(pms);

                    con.Open();

                    string msg = com.ExecuteNonQuery()>0?"存入成功":"存入失败";

                    MessageBox.Show(msg);

                }

            }

        }

        /// <summary>

        /// 从数据库中读取

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void button3_Click(object sender, EventArgs e)

        {

            string conStr = "Data Source=.;Initial Catalog=MyFirstDatabase;User Id=sa;PassWord=自己的密码";

            using(SqlConnection con=new SqlConnection(conStr))

            {

                //sql语句

                string sql = "select * from ImageTest";

                using (SqlCommand com = new SqlCommand(sql, con))

                {

                    con.Open();

                   using(SqlDataReader reader=com.ExecuteReader())

                    {

                        if (reader.HasRows)

                        {

                            //声明一字节数组   将数据库中的图片现存入字节数组中

                            byte[] imageByte;

                            //在这我是知道里面就一张图，所以这么写的，个人根据实际情况，可做修改

                           while(reader.Read())

                            {

                                //将图片转换为字节数组

                                imageByte = (byte[])reader["UserImage"];

                                //转换为文件流

                                MemoryStream stream = new MemoryStream(imageByte);

                                //再将文件流 转换为 图像

                                Bitmap bitmap = new Bitmap(stream);

                                pictureBox1.Image = bitmap;

                            }

                        }

                    }

                }

            }

        }

    }

}