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Draw initial query tree

Consider the SQL Query given below. Draw initial query tree and transform this initial query tree using heuristic query optimization

SELECT p. ticketno

FROM Flight as F, Passenger as P, Crew as C

WHERE F.Flightno=c.flightno AND

F.Date=’06-23-15’AND

F.to=’Mumbai’ AND

P.name=C.name

Mumbai University > Information Technology > Sem 3 > Database Management System

Marks: 10M

Year: May 2016

1 Answer
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Step 1: Converting Expression to basic Relational Form

πp.ticketnoσf.flightn0 = p.flightno

AND f.flightno = c.flightno

AND F.Date=’06-23-15’

AND F.to=’Mumbai’

AND p.name=c.name

Step 2: Drawing initial query tree using SQL query

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Step 3: Moving SELECT operators down the tree

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Step 4: Apply more restrictive SELECT operation First

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Step 5: Replacing Cartesian Product with JOIN Operation.

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Step 6: Replacing Cartesian Product with JOIN Operation.

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