rollback another user's transaction

[mahajanakhil198]

It gives you the sid of the blocking session which you can use to query v$session, which gives you the current sql id of what they are running which you can use to find the blocking sql.

Man, that's what I posted. Why is it(SQL_ID column of v$session) showing NULL value?

That's why, wanted to know any alternative way to find blocking SQL.