When you describe a specific, known noun using a relative clause (a clause starting with che, meaning "that" or "who"), you use the normal indicative mood. However, if you are describing a noun that is undefined, merely desired, or might not even exist, you must use the subjunctive mood.
You will frequently use this when searching for something with specific requirements—like a cozy venue or a late-night pub—without knowing if you will actually find it.
| We are looking for a pub that has craft beer. | Cerchiamo un pub che abbia birra artigianale. |
| We must find a nighttime venue that is cozy. | Dobbiamo trovare un locale notturno che sia accogliente. |
Similarly, you use the subjunctive when asking if something matching your description exists.
| Is there a pub here that has a billiards table? | C'è un pub qui che abbia un biliardo? |
| Do you know a venue that stays open until dawn? | Conosci un locale che resti aperto fino all'alba? |
Finally, if you declare that no such thing exists, the thing you are describing is entirely non-existent. In Italian, you must use the subjunctive after negative expressions like non conosco nessun (I don't know any) or non c'è nessuna (there is no).
| I don't know any nighttime venue that serves hot drinks. | Non conosco nessun locale notturno che serva bevande calde. |
| There is no nightclub here that is open until dawn. | Non c'è nessuna discoteca qui che sia aperta fino all'alba. |
Notice the subjunctive forms of regular verbs in these relative clauses. For verbs ending in -ere and -ire like servire (to serve) and vendere (to sell), the singular subjunctive ending is -a (e.g., serva, venda). For -are verbs, it is -i.
| I am looking for a pub that serves craft beer. | Cerco un pub che serva birra artigianale. |
| I am looking for a supermarket that sells cold beer. | Cerco un supermercato che venda birra fredda. |
