Convert SQLite Database into ROOT TTree

ROOT
5

Hi,

Thanks for your reply. In the meantime, I had solved the issue like this :

  TFile f("../data/input_samples.root","RECREATE");
  TTree T("ntuple","data from ascii file");
  Long64_t nlines = T.ReadFile("../data/input_samples.csv",csv_format.c_str());
  printf(" found %lld points\n",nlines);
  T.Write();

The csv_format is a std::string which contains the names of the vars and their type (the header of the CSV file). The issue with this approach is that I can’t easily infer the type of the columns from the file (not all my columns are floating point numbers).

So I am back to the SQLite as suggested file without going through the CSV conversion. I am trying something like this:

  auto dbname = "sqlite://../data/input_samples.sqlite";
  auto username = "";
  auto userpass = "";
  auto f = new TSQLFile(dbname, "open", username, userpass);
  f->ls();

But there seems to be a problem that I don’t understand, since I get the following message when I run this code:

Error in <TSQLFile::TSQLFile>: DB sqlite://../data/input_samples.sqlite tables not exist
TSQLFile**		sqlite://../data/input_samples.sqlite	TFile interface to SQL DB
 TSQLFile*		sqlite://../data/input_samples.sqlite	TFile interface to SQL DB

I don’t think that there is a problem with my file, since the following works:


  TSQLServer *db = TSQLServer::Connect("sqlite://../data/input_samples.sqlite","", "");
  printf("Server info: %s\n", db->ServerInfo());

  TSQLRow *row;
  TSQLResult *res;

  // list tables in database "test" (the permission tables)
  printf("\nList all tables in database\n",
         db->GetHost());
  res = db->GetTables("");
  while ((row = res->Next())) {
  printf("%s\n", row->GetField(0));
  delete row;
  }
  delete res;

  auto* cols = db->GetTableInfo("selection")->GetColumns();

  for(const auto&& col : *cols) 
    {
    col->Print();
    std::cout << "Name " << col->GetName() << '\n';
    }

The col->Print() gives the correct information and col->GetName() also.

Now I am stuck retrieving the types of the columns, because

col->GetSQLType()

does not compile:

‘class TObject’ has no member named ‘GetSQLType’

and if I do:

std::cout << "SQL type " << ((TSQLColumnInfo*)col)->GetSQLType() << '\n';

I get -1; which means that something is wrong.

Any ideas?

Thanks.

Garjola.