Please translate to english

[Inoue]

I bought the book, which proved to be my mistake.

Please translate the above sentence to Russian and explain about that grammer.

thanks

[loner]

В зависимости от контекста:
Я приобрел книгу, но как оказалось, не ту/зря/я допустил промашку.

[Inoue]

Which(relative pronoun) can be replaced by что?

[loner]

Подстрочник:
Я (типа) купил (типа) книгу, что оказалось (типа) моей ошибкой. )

[Inoue]

Thanks a lot.

The grammer in the russian sentence is correct? что is relative pronoun?

What is the antecedent?

[loner]

I think my is a personal noun - мой.
There are only five relative nouns *that, which, who, whom, and whose*, ain't there?
May be it is more grammatically correct, in my books, to say like that:
Я купил книгу, и это оказалось ошибкой.
Replacing the object clause with the conjunctive clause.
**What is the antecedent?** What do u imply by antecedent?

[Inoue]

The antecedent of relative pronoun "что" is usually "то"?

[loner]

English: I bought the book, which proved to be my mistake
Russian: Я купил книгу, что оказалось моей ошибкой.
The sentence (English/Russia) is complex with an object clause joining the primary clause by means of the relative noun 'which'. As simple as that. ) Is there anything else that is not clear?

[Inoue]

Thanks a lot. I have been studying both language for a long time, however, I have not understood such a usagge of relative pronouns yet.