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hi,

 

sorry, i have a question to do...but i know how to write in sql query ....however the answer need to write on relational algebra

 

in query is like :

 

SELECT * FROM operation
where r='broken'
group by pc
having count(pc) >1 ;
π id,pc,result ( σ r = 'broken' (operation))
like group by and having clasue...i no idea ...
i searched on internet still @@ ....
isnt the answer like that, i using split/step by step method to do
rel 1 = σ r = 'broken' (operation)
rel 2 = σ count(pc)>1 γ pc,count(pc) (rel 1))
rel 3 = π id,pc,result (rel 2 )
thanks
Edited by HarrySeah

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To: justsomeguy

 

thank you so much for help,

yes that page i was viewed before ...but that answer quite ... some confusing ..

by the way , thanks :good:

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