| Oracle Newbie, help needed [message #2484] |
Fri, 19 July 2002 08:58  |
orawhizkid
Messages: 1
Registered: July 2002
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Junior Member |
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Hi,
I am a prime java programmer and have little exposure to oracle. I am preparing for an interview whcih needs heavy oracle exp. I want to know the answers to the following qstns. Any help is greatly appreciated.
2.What's the difference between Union and Union All?
3.Which one is better Join or Subquery and why
4.What is corelated subqueries
5.What is outer join?
6. Can u define view on top of view?
7.Can u do normal sql operation like insert and update on view.
7.What's the difference between intersection and minus?
8.What r the responsibilities of sysadmin
9.What's record type and table of records in pl/sql?
10.What r the new features of oracle 9i
11.When do we get "fetch out of sequence error" or "cursor out of size" error?
12 What does "SELECT FOR UPDATE" do?
13. Why is it recommended to use NOWAIT in select for update?
14. What are the different kinds of Transaction Isolation level?
15. What should we use BETWEEN and IN
16 What is Materialized View?
17 What is deferred constraints
18 What is UPDATE Batching?
19. What is Connection pooling
20 What is Scrollable recordset?
21 What is the relevance of autoCommit?
22 What is the different kind of Locks?
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| Re: Oracle Newbie, help needed [message #2509 is a reply to message #2484] |
Mon, 22 July 2002 11:35  |
Raj
Messages: 411
Registered: November 1998
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Senior Member |
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2. Union All will display even duplicate rows also, Union will display only distinct rows.
3. Join is better, Subquery will take more time to compile.
4. Correlated Sub Querie is refering main queries table columns in sub query is Correlated Sub Querie.
5. Outer join is one of join types, this join will retrieve un matching rows from the other table, if you have emp and dept tables and want to join both tables want to see all the deptments even they are not used in emp table then outer join can be used.
6. We can define a view on top of view.
7. Yes you can
Intersection retrieves common rows between two tables,
Minus will retrieve which are in one table but not in other table. If we have 1,2,3,4 in table1 1,2 in table2. table1 - table2 will give 3,4 as result.
8. Sysadmin can create users, backups, restoring the database, creating database
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