.net core 从数据库读取图片和保存图片到数据库

using Microsoft.Data.SqlClient;
using System.Data;

namespace PhotoApp;

internal class PhotoHelper
{
    string createTableSql = @"CREATE TABLE [dbo].[Employee](
                             [emp_id] [int] NOT NULL,
                             [emp_name] [varchar](50) NOT NULL,
                             [emp_image] [image] NULL
                         ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]";
    string connectionString = "Server=192.168.10.xxx;User Id=xxx;Password=xxx;Database=TestPhoto;Trusted_Connection=false;TrustServerCertificate=True";
    public string getPhotoPath = @"D:\Dragon.png";
    public string savePhotoPath = @"D:\test.png";
    public void SavePhotoToSqlServer()
    {
        using (SqlConnection sqlConnection = new SqlConnection(connectionString))
        {
            FileInfo finfo = new FileInfo(getPhotoPath);
            byte[] btImage = new byte[finfo.Length];
            FileStream fStream = finfo.OpenRead();
            fStream.Read(btImage, 0, btImage.Length);
            fStream.Close();
            using (SqlCommand sqlCommand = new SqlCommand(
                  "INSERT INTO Employee (emp_id, emp_name, emp_image) VALUES(@emp_id, @emp_name, @emp_image)",
                  sqlConnection))
            {
                sqlCommand.Parameters.AddWithValue("@emp_id", 2);
                sqlCommand.Parameters.AddWithValue("@emp_name", "Employee Name");
                SqlParameter imageParameter = new SqlParameter("@emp_image", SqlDbType.Image);
                imageParameter.Value = btImage;
                sqlCommand.Parameters.Add(imageParameter);
                sqlConnection.Open();
                sqlCommand.ExecuteNonQuery();
                sqlConnection.Close();
            }
        }
    }

    public string createTableSql2 = @"CREATE TABLE [dbo].[ImageFile](
                                        [Id] [UNIQUEIDENTIFIER] NOT NULL,
                                        [Name] [NVARCHAR](200) NULL,--文件名
                                        [Type] [NVARCHAR](50) NULL,--文件类型
                                        [Image] [IMAGE] NULL--文件
                                    )";
    public void SaveBulkPhotosToSqlServer()
    {
        using (SqlConnection myconn = new SqlConnection(connectionString))
        {
            myconn.Open();
            using (SqlCommand mycomm = new SqlCommand())
            {
                DirectoryInfo dir = new DirectoryInfo(savePhotoPath);
                foreach (FileInfo item in dir.GetFiles("*.png"))//循环读取文件夹内的png文件
                {
                    //var pic = getJpgSize(item.FullName);
                    string str = string.Format("insert into ImageFile (Id,Name,Type,Image) values('{0}','{1}','{2}',@Image)", Guid.NewGuid().ToString(), Path.GetFileNameWithoutExtension(item.FullName), item.Extension.Substring(1));//插入数据
                    mycomm.CommandText = str;
                    mycomm.Connection = myconn;
                    FileStream fs = new FileStream(item.FullName, FileMode.Open);
                    BinaryReader br = new BinaryReader(fs);
                    Byte[] byData = br.ReadBytes((int)fs.Length);
                    fs.Close();
                    mycomm.Parameters.Add("@Image", SqlDbType.Binary, byData.Length);
                    mycomm.Parameters["@Image"].Value = byData;
                    mycomm.ExecuteNonQuery();
                    mycomm.Parameters.Clear();
                }
            }
        }
    }

    public void ReadPhotoFromSqlServer(int userId)
    {
        using (SqlConnection sqlconnection = new SqlConnection(connectionString))
        {
            sqlconnection.Open();
            string sqlQuery = string.Format(@"Select [emp_image] From [Employee] Where [emp_id]={0}", userId);

            // Read Image Value from Sql Table 
            SqlCommand sqlCommand = new SqlCommand(sqlQuery, sqlconnection);            
            using (SqlDataReader reader = sqlCommand.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["emp_image"];
                        //转换为文件流
                        MemoryStream ms = new MemoryStream(imageByte);
                        ms.Seek(0, SeekOrigin.Begin);
                        using (var output = File.OpenWrite(savePhotoPath))
                        {
                            ms.CopyTo(output);
                        }

                        ////再将文件流转换为图像
                        //Bitmap bitmap = new Bitmap(stream);
                        //pictureBox1.Image = bitmap;
                    }
                }
            }
        }
    }

    public void SaveImageFromBase64(string base64string)
    {
        byte[] b = Convert.FromBase64String(base64string);
        //实际情况需要根据base64判断文件后缀名
        string path = Path.Combine(savePhotoPath, "test", "abc.jpg");
        File.WriteAllBytes(path, b);
    }
}

参考资料：

Saving an Image to SQL Server - CodeProject

SQLserver用Image格式储存图片 - Murphy丶悦 - 博客园 (cnblogs.com)

关于c＃：将MemoryStream转换为FileStream时FileStream数据不完整 | 码农家园 (codenong.com)