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What is the fastest way of accessing a row in a table ?
Using ROWID.CONSTRAINTS
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What is an Integrity Constraint ?
Integrity constraint is a rule that restricts values to a column in a table.
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What is a database link ?
Database Link is a named path through which a remote database can be accessed.
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How to access the current value and next value from a sequence ? Is it possible to access the current value in a session before accessing next value ?
Sequence name CURRVAL, Sequence name NEXTVAL.It is not possible. Only if you access next value in the session, current value can be accessed.
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What are the advantages of VIEW ?
To protect some of the columns of a table from other users.To hide complexity of a query.To hide complexity of calculations.
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What is the use of TNSNAME.ORA and LISTENER.ORA files
tnsnames.ora is used to connect to the remote db. To get the connection listener.ora should be configured at the server and it should be up and running.
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What is a transaction ?
Transaction is logical unit between two commits and commit and rollback.
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Explain UNION,MINUS,UNION ALL, INTERSECT ?
INTERSECT returns all distinct rows selected by both queries.MINUS - returns all distinct rows selected by the first query but not by the second.UNION - returns all distinct rows selected by either queryUNION ALL - returns all rows selected by either query, including all duplicates.
SQL*Plus interview Questions
Ans