Sqlite3 - выводит ошибку SQLITE_MISUSE

 class SQL { public:
    SQL();
    ~SQL();
 
    int openConnect(sqlite3 *pDB, const char db_name[]);
    void closeConnect(sqlite3 *pDB);
    int prepareQuery(sqlite3 *pDB, const char *zSql, int nByte = -1, sqlite3_stmt **ppSTMT = 0, const char
**pzTail = 0);
    int step(sqlite3_stmt *pSTMT);
 
};

int SQL::openConnect(sqlite3 *pDB, const char db_name[]) {
    return sqlite3_open(db_name, &pDB);
}
 
void SQL::closeConnect(sqlite3 *pDB) {
    sqlite3_close(pDB);
}
 
int SQL::prepareQuery(sqlite3 *pDB, const char *zSql, int nByte, sqlite3_stmt **ppSTMT, const char **pzTail) {
    return sqlite3_prepare(pDB, zSql, nByte, ppSTMT, pzTail);
}
 
int SQL::step(sqlite3_stmt *pSTMT) {
    return sqlite3_step(pSTMT);
}

int main()
{
 
    sqlite3 *db;
    int rc;
    char db_name[] = "just_db.sqlite";
    const char *db_query = "insert into `user` values ('hey');";
 
    SQL *sql;
 
    rc = sql->openConnect(db, db_name);
 
    if (rc != SQLITE_OK) {
        std::cout << "Erro: " << sqlite3_errmsg(db);
    }
 
    std::cout << rc << std::endl;
 
    sqlite3_stmt *statement;
 
    rc = sql->prepareQuery(db, db_query, -1, &statement, NULL);
 
    if (rc == SQLITE_OK) {
        std::cout << "Some error: " << sqlite3_errmsg(db);
    }
 
    std::cout << rc << std::endl;
 
    rc = sql->step(statement);
 
    if (rc == SQLITE_ERROR) {
        std::cout << "SOME ERROR: " << sqlite3_errmsg(db);
    }
 
    std::cout << rc << std::endl;
 
    sql->closeConnect(db);
 
  return 0;
}

if (rc == SQLITE_ERROR) {
        std::cout << "SOME ERROR: " << sqlite3_errmsg(db);
    }

int SQL::openConnect(sqlite3 *&pDB, const char db_name[]) {
return sqlite3_open(db_name, &pDB);
}

int SQL::openConnect(sqlite3 **ppDB, const char db_name[]) {
return sqlite3_open(db_name, ppDB);
}