How to backup Sql Database Programmatically in C#

you can connect to the database using SqlConnection and SqlCommand and execute the following command text for example:

BACKUP DATABASE [MyDatabase] TO  DISK = 'C:\....\MyDatabase.bak'

See here for examples.

It's a good practice to use a config file like this:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings>
    <add name="MyConnString" connectionString="Data Source=(local);Initial Catalog=MyDB; Integrated Security=SSPI" ;Timeout=30"/>
  </connectionStrings>
  <appSettings>
    <add key="BackupFolder" value="C:/temp/"/>
  </appSettings>
</configuration> 

Your C# code will be something like this:

// read connectionstring from config file
var connectionString = ConfigurationManager.ConnectionStrings["MyConnString"].ConnectionString; 

// read backup folder from config file ("C:/temp/")
var backupFolder = ConfigurationManager.AppSettings["BackupFolder"];

var sqlConStrBuilder = new SqlConnectionStringBuilder(connectionString);

// set backupfilename (you will get something like: "C:/temp/MyDatabase-2013-12-07.bak")
var backupFileName = String.Format("{0}{1}-{2}.bak", 
    backupFolder, sqlConStrBuilder.InitialCatalog, 
    DateTime.Now.ToString("yyyy-MM-dd"));

using (var connection = new SqlConnection(sqlConStrBuilder.ConnectionString))
{
    var query = String.Format("BACKUP DATABASE {0} TO DISK='{1}'", 
        sqlConStrBuilder.InitialCatalog, backupFileName);

    using (var command = new SqlCommand(query, connection))
    {
        connection.Open();
        command.ExecuteNonQuery();
    }
}

Works for me:

public class BackupService
{
    private readonly string _connectionString;
    private readonly string _backupFolderFullPath;
    private readonly string[] _systemDatabaseNames = { "master", "tempdb", "model", "msdb" };

    public BackupService(string connectionString, string backupFolderFullPath)
    {
        _connectionString = connectionString;
        _backupFolderFullPath = backupFolderFullPath;
    }

    public void BackupAllUserDatabases()
    {
        foreach (string databaseName in GetAllUserDatabases())
        {
            BackupDatabase(databaseName);
        }
    }

    public void BackupDatabase(string databaseName)
    {
        string filePath = BuildBackupPathWithFilename(databaseName);

        using (var connection = new SqlConnection(_connectionString))
        {
            var query = String.Format("BACKUP DATABASE [{0}] TO DISK='{1}'", databaseName, filePath);

            using (var command = new SqlCommand(query, connection))
            {
                connection.Open();
                command.ExecuteNonQuery();
            }
        }
    }

    private IEnumerable<string> GetAllUserDatabases()
    {
        var databases = new List<String>();

        DataTable databasesTable;

        using (var connection = new SqlConnection(_connectionString))
        {
            connection.Open();

            databasesTable = connection.GetSchema("Databases");

            connection.Close();
        }

        foreach (DataRow row in databasesTable.Rows)
        {
            string databaseName = row["database_name"].ToString();

            if (_systemDatabaseNames.Contains(databaseName))
                continue;

            databases.Add(databaseName);
        }

        return databases;
    }

    private string BuildBackupPathWithFilename(string databaseName)
    {
        string filename = string.Format("{0}-{1}.bak", databaseName, DateTime.Now.ToString("yyyy-MM-dd"));

        return Path.Combine(_backupFolderFullPath, filename);
    }
}