mysql - Determine entrys with "missing" subsequent entry in SQL -
i have table in sql represent sort of events. try determine lines specific event not "followed" specific event. in table below lines signed did not sign out afterwards (lucy , joe). achievable sql , if yes how?
|id|name |event | ========================== |01|fred |sign | ------------------------- |02|joe |sign | -------------------------- |03|lucy |sign | -------------------------- |04|joe |do foo | -------------------------- |05|joe |sign out | -------------------------- |06|joe |sign | -------------------------- |07|fred |sign out | --------------------------
many thanks
select * table t1 left outer join table t2 on(t1.name=t2.name , t2.event='sign out') t1.event='sign up' , t2.name null
there's no such thing "followed by" unless define you'll need provide more info. (it might adding "t1.id >t2.id" in on clause)
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