INTERVIEW QUESTIONS ORACLE DETAILS

Question: Diffrence between VIEW and MATERIALIZED VIEW?

Answer: Views are the latest snapshot of the database at any instance of time..whereas Mat Views are the snapshots of Database at a particular instance.
For Eg: If there exists a table Emp containing 10 records against which there is a view Like (Select emp, emp_id from emp)
and there exists a MAT view with the same query( Select emp, emp_id from emp), if you fire a query at let say 10.15 a.m as SELECT * FROM EMP_VIEW This will return 10 records, If you fire the same query against MVIEw it will retuen 10 records. If aat 10.30 I insert one more record in emp table and then If I fire a query SELECT * from EMP_VIEW it will return me 10 rows but the MVIEW query will still return me 10 rows as it is the snapshot of the database at 10.15

Views are the latest snapshot of the database at any instance of time..whereas Mat Views are the snapshots of Database at a particular instance.
For Eg: If there exists a table Emp containing 10 records against which there is a view Like (Select emp, emp_id from emp)
and there exists a MAT view with the same query( Select emp, emp_id from emp), if you fire a query at let say 10.15 a.m as SELECT * FROM EMP_VIEW This will return 10 records, If you fire the same query against MVIEw it will retuen 10 records. If aat 10.30 I insert one more record in emp table and then If I fire a query SELECT * from EMP_VIEW it will return me 10 rows but the MVIEW query will still return me 10 rows as it is the snapshot of the database at 10.15 Source: CoolInterview.com

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