//app.component.ts
import {MyService} from './myservice.service';
...
export class AppComponent{

constructor(
private myS: MyService,
){}

callDb(){
this.myS.getDB()

//qui non so come recuperare il risulato
}
}

----------------------------------------------------------------------------------------------

//mysrervice.service.ts
import { HttpClient, } from '@angular/common/http';
...

export class MyService{
url= "my.url.db"
myLista= [];

  constructor(private http: HttpClient) { }

getDB(){
this.http.get<any[]>(`${this.url}`)
.subscribe( res =>
		this.myLista = res;
}

}