I recently started learning bioinformatics for my final thesis and I am doing MiRNA analysis in R. I am trying to obtain the ensembl id from the mirbase IDs (e.g. hsa-miR-3138) from my dataset. I am doing: select(org.Hs.eg.db, keys = mirna[,1], columns = c("ENSEMBL"))

What I am missing here is the "keytype" I guess. What should I use in that case? I went through the list of keytypes I can use but none of them seem to match with mirbaseIDs.

Also, I am doing this in order to perform GSEA on my dataset, however, I have seen that some people recommend to find the target genes first with some target prediction tool, and do the analyses based on that. I would appreciate it if someone could give me some advice as to how should I do the analyses for my miRNAs as I am very new with this and I am a bit lost.

Thank you in advance.