How to support such a statement "ATTACH DATABASE x AS y KEY z"?

How to support such a statement "ATTACH DATABASE x AS y KEY z"?

```
sqlite3* db = 0;
ret = sqlite3_open("test2.db", &db);
std::string sqlTemp = "ATTACH DATABASE 'test2.db' AS test2 KEY '123456';";
sqlite3_exec(db, sqlTemp.c_str(), NULL, NULL, &pErrMsg);
```

But it made a mistake: file is not a database.