将存照片的字段设为image类型。

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 PhotoSQL
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

    string sqlCon = "";  
    private void button1\_Click(object sender, EventArgs e)  
    {  
        string url = @"C:\\Users\\jinwei\\Desktop\\tiger.jpg";  
        byte\[\] dd = GetPictureData(url);

        ImgToDB(dd);//保存到数据库中  
    }

    private void button2\_Click(object sender, EventArgs e)  
    {  
        ImgDBTo();  
    }

    /// <summary>  
    /// 保存到数据库  
    /// </summary>  
    /// <param name="imgBytesIn"></param>  
    private void ImgToDB(byte\[\] imgBytesIn)  
    {  
        try  
        {  
            SqlConnection con = new SqlConnection("server=SDSC2-1,1433;uid=sa;pwd=jinwei;database=web");  
            con.Open();  
            SqlCommand cmd = new SqlCommand("insert  into aaaa (img) values( @Image ) ;", con);  
            cmd.Parameters.Add("@Image", SqlDbType.Image);  
            cmd.Parameters\["@Image"\].Value = imgBytesIn;  
            cmd.ExecuteNonQuery();

            con.Close();  
            MessageBox.Show("图片上传成功");

        }  
        catch  
        {  
            MessageBox.Show("您选择的图片不能被读取或文件类型不对！", "错误", MessageBoxButtons.OK, MessageBoxIcon.Warning);

        }

    }

    /// <summary>  
    /// 从数据库中  图片 并且保存到C盘  
    /// </summary>  
    public void ImgDBTo()  
    {  
        byte\[\] MyData = new byte\[\];  
        using (SqlConnection conn = new SqlConnection("server=SDSC2-1,1433;uid=sa;pwd=jinwei;database=web"))  
        {  
            conn.Open();  
            SqlCommand cmd = new SqlCommand();  
            cmd.Connection = conn;  
            cmd.CommandText = "select \* from aaaa";  
            SqlDataReader sdr = cmd.ExecuteReader();  
            sdr.Read();  
            object o = sdr\["img"\];  
            MyData = (byte\[\])sdr\["img"\];//读取第一个图片的位流  
            int ArraySize = MyData.GetUpperBound();//获得数据库中存储的位流数组的维度上限，用作读取流的上限

            FileStream fs = new FileStream(@"c:\\00.jpg", FileMode.OpenOrCreate, FileAccess.Write);  
            fs.Write(MyData, , ArraySize);  
            fs.Close();   //-- 写入到c:\\00.jpg。  
            conn.Close();  
            Console.WriteLine("读取成功");//查看硬盘上的文件  
        }  
    }

    /// <summary>  
    /// 根据路径将图片转换成 byte\[\]  
    /// </summary>  
    /// <param name="imagepath"></param>  
    /// <returns></returns>  
    public byte\[\] GetPictureData(string imagepath)  
    {  
        /\*\*/  
        ////根据图片文件的路径使用文件流打开，并保存为byte\[\]  
        FileStream fs = new FileStream(imagepath, FileMode.Open);//可以是其他重载方法  
        byte\[\] byData = new byte\[fs.Length\];  
        fs.Read(byData, , byData.Length);  
        fs.Close();  
        return byData;  
    }  
}  

}

转载来源：

https://www.cnblogs.com/cl1006/p/10181520.html