String csv = 'Id,Name\n';
for ( List<Account> accts : [ SELECT id, name FROM Account LIMIT 10 ] ) {
  for ( Account acct : accts ) {
    csv += acct.id + ',' + acct.name.escapeCsv() + '\n';
  }
}
 
ContentVersion file = new ContentVersion(
  title = 'accounts.csv',
  versionData = Blob.valueOf( csv ),
  pathOnClient = '/accounts.csv'
);
 
insert file;
System.debug( file );