Nested Queries-SQL.ppt

JayavarapuKarthikJ1 375 views 11 slides Aug 23, 2022

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Database Management Systems

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Language: en

Added: Aug 23, 2022

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Nested Queries
OneofthemostpowerfulfeaturesofSQLisnested
queries
Anestedqueryisaquerythathasanotherquery
embeddedwithinittheembeddedqueryiscalleda
subquery.
AsubquerytypicallyappearswithintheWHEREclauseof
aquery
SubqueriescansometimesappearintheFROMclause
ortheHAVINGclause

GROUP BY and HAVING Clauses
wehaveappliedaggregateoperationstoall
(qualifying)rowsinarelation.
Oftenwewanttoapplyaggregateoperationsto
eachofanumberofgroupsofrowsinarelation,
wherethenumberofgroupsdependsontherelation
instance