In Latin the subjunctive can express the ideas of:
wish, command, purpose, result, characteristic, circumstances 
indirect question, indirect discourse and so on. 

Subjunctive Present 
- jussive: a command or prohibition (ne +) in the First and Third person
  Veniamus. Let us come.
  Servus id faciat. Let the slave do it.
  Ne redeant. Let them not return.
- a wish for the future (utinam +)
  Utinam falsus vates sim. O that I may be a false prophet.
- condition 'should''would' (future less vivid)
  Si id faciat, prudens sit. If he should do it, he would be wise.
- dubitative
  Quis me reprehendat? Who is to blame me (I wonder)?.
  Quid faciat? What is he to do (I wonder)?.
- sequence of tenses: [main verb in present or future] action at the same time or after 
  *indirect question 
  Rogant (rogabunt) quid faciat. They ask (will ask) what he is doing (will do).
  *purpose
  Id facit (faciet) ut me juvet. He does (will do) it to help me.
  *indirect discourse
  Puto eos malos qui in urbe maneant infirmos futuros esse sine duce. 
  I think that those evil men who remain in the city will be weak without their leader.
  
Subjunctive Imperfect 
- a wish for the present (utinam +)
  Utinam ne adesses. Would that you were not here.
- condition contrary to fact present
  Si id faceret, prudens esset. If he were doing it, he would be wise.
  Si hoc diceret, erraret. If he were saying this, he would be wrong.
- sequence of tenses: [main verb in past tenses] action at the same time or after 
  *indirect question
  Rogaverunt (rogabant) quid feceret. They asked (kept asking) what he is doing (will do).
  *circumstances
  Cum hoc sciret, potuit eos juvare. Since he know this, he was able to help them.
  result
  Tanta fecit ut urbem servaret. He did such great things that he saved the city
  *purpose
  Haec fecit ut urbem servaret. He did these things that he might saved the city
  Id fecit (faciebat) ut me juvaret. He did (kept doing) it to help me.
  Hoc fecit (faciebat) ne caperetur. He did (kept doing) this that he might not be captured.

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Subjunctive Perfect 
- sequence of tenses: [main verb in present or future] action before 
  *indirect question
  Rogant (rogabunt) quid fecerit. They ask (will ask) what he did.
  *indirect discourse
  Nescio quando redieris. I do not know when you returned.
  *verb of doubting
  Non dubitamus quin novae copiae pervenerint. We do not doubt that reinforcements have arrived.


Subjunctive Pluperfect  
- a wish for the past (utinam +)						
  Utinam Romae mansisses. If only you had stayed in Rome.
- condition contrary to fact past
  Si id fecisset, prudens fuisset. If he had done it, he would have been wise.
  Si hoc dixisset, erravisset. If he had said this, he would have been wrong.
- sequence of tenses: [main verb in past tenses] action before 
  *indirect question
  Rogaverunt (rogabant) quid fecisset. They asked (kept asking) what he had done.
  *circumstances
  Cum hoc fecisset, ad te fugit. When he had done this, he fled to you.
  *indirect discourse
  Dixit se legisse libros quos misisses. He said that he had read the books which you had sent.