C#读取Mysql blob字段 (转帖)
时间:2022-03-14 04:28
开发环境:Windows XP Professional SP3、VS2008、Winform、MySQL5.0、MySQL.Data.dll 6.2.3.0
1、从硬盘上读取一图片,将其转化为流,然后存储到此BLOB字段中
[csharp]
- private void button1_Click(object sender, EventArgs e)
- {
- byte[] bytes = null;
- bytes = File.ReadAllBytes(@"C:/Documents and Settings/user/My Documents/My Pictures/11.jpg");
- using (MySql.Data.MySqlClient.MySqlConnection conn = new MySql.Data.MySqlClient.MySqlConnection())
- {
- conn.ConnectionString = ConfigurationManager.ConnectionStrings["test"].ConnectionString;
- MySql.Data.MySqlClient.MySqlCommand cmd = new MySql.Data.MySqlClient.MySqlCommand();
- cmd.CommandText = "insert into test(id,picture) values(@id,@picture)";
- cmd.CommandType = CommandType.Text;
- cmd.Parameters.Add("@id", MySql.Data.MySqlClient.MySqlDbType.Int32);
- cmd.Parameters.Add("@picture", MySql.Data.MySqlClient.MySqlDbType.Blob);
- cmd.Parameters[0].Value = 15;
- cmd.Parameters[1].Value = bytes;
- cmd.Connection = conn;
- conn.Open();
- int affectedrows = cmd.ExecuteNonQuery();
- cmd.Dispose();//此处可以不用调用,
- conn.Close();// 离开 using 块, connection 会自行关闭
- }
- }
2、读取此BLOB字段,将其转化为图片显示在Picturebox控件上
[csharp]- private void button2_Click(object sender, EventArgs e)
- {
- using (MySql.Data.MySqlClient.MySqlConnection conn = new MySql.Data.MySqlClient.MySqlConnection())
- {
- conn.ConnectionString = ConfigurationManager.ConnectionStrings["test"].ConnectionString;
- conn.Open();
- MySql.Data.MySqlClient.MySqlCommand cmd = new MySql.Data.MySqlClient.MySqlCommand();
- cmd.CommandType = CommandType.Text;
- cmd.CommandText = "select id,picture from test where id = 11";
- cmd.Connection = conn;
- System.Data.Common.DbDataReader reader = cmd.ExecuteReader();
- byte[] buffer = null;
- if (reader.HasRows)
- {
- reader.Read();
- long len = reader.GetBytes(1, 0, null, 0, 0);//1是picture
- buffer = new byte[len];
- len = reader.GetBytes(1, 0, buffer, 0, (int)len);
- System.IO.MemoryStream ms = new System.IO.MemoryStream(buffer);
- System.Drawing.Image iamge = System.Drawing.Image.FromStream(ms);
- pictureBox1.Image = iamge;
- }
- }
- }
数据库相关文件配置在App.config中,如果不用配置文件,可以写成:
string remote = "Persist Security Info=False;database=数据库名;server=服务器IP;user id=用户名;pwd=密码";
然后conn.ConnectionString = remote;即可。
后记:
之前在.net中用的mysql库是:MySQLDriverCS,但是一直没有搞定,而且用官方给的读取blob字段也失败。于是改用MySql.Data.dll ,注意Mysql.Data5.0版本不支持读取Blob字段,所以需要用较高版本,我用的是MySQL.Data.dll 6.2.3.0。
MySql.Data.dll 6.2.3.0下载地址:
MySql.Data.dll 5.0.9.0下载地址: