"i dont know who is the boy" & "i dont know who the boy is"

第二个正确,因为所有的从句中,语序都用陈述语序.如I dont know who you are.
再问： Thank you ,But some times i got confuse , for example :" i dont know who is in the room ".
再答： 这不也是陈述句吗， who is in the room. who 是主语