• What is the difference between unique key and primary key ?
Answer: Unique key can be null; Primary key cannot be null.
• An insert statement followed
by a create table statement followed
by rollback ? Will the
rows
be inserted ?
Answer: No.
• Can you define multiple savepoints ?
Answer: Yes.
• Can you Rollback to any savepoint
?
Answer: Yes.
• What is the
maximum no.of columns a table can have ?
Answer: 254.
• What is the significance of the & and && operators in PL SQL ?
Answer: The & operator means that the PL SQL block requires user
input for a variable.
The && operator means that the
value of this variable should be the same
as inputted by the user
previously for this same variable
• Can you pass a parameter to a cursor ?
Answer: Explicit cursors can take
parameters, as the example below shows.A cursor parameter can
appear in a query wherever a constant can appear.
CURSOR c1 (median IN NUMBER) IS
SELECT job, ename FROM emp WHERE sal >
median;
• What are the various types of RollBack
Segments ?
Answer: The types of Rollback sagments are as follows :
Public Available to all instances
Private Available to specific
instance
• Can you use %RowCount as a parameter to a
cursor ?
Answer: Yes
• Is the query below allowed :
Select sal, ename Into x From emp Where ename = 'KING' (Where x is a
record of Number(4)
and Char(15))
Answer: Yes
• Is the assignment given below allowed
:
ABC = PQR (Where ABC and PQR are records)
Answer: Yes
• Is this for loop allowed :
For x in
&Start..&End
Loop
Answer: Yes
• How many rows will the following SQL return :
Select * from emp Where rownum <
10;
Answer: 9 rows
• How many rows will the following SQL return :
Select * from emp Where rownum = 10;
Answer: No rows
• Which symbol preceeds the path to the table in the remote database ?
Answer: @
• Are views automatically updated when base tables are updated
?
Answer: Yes
• Can a trigger written for a view ?
Answer: No
• If all the values from a cursor have been
fetched and another fetch is issued, the output
will
be : error, last record or first record
?
Answer: Last Record
• A table has the following data : [[5,
Null, 10]].What will the average
function return ?
Answer: 7.5
• Is Sysdate a system variable or a system function?
Answer: System
Function
• Consider a sequence whose currval is 1 and
gets incremented by 1 by using the nextval
reference we get the next number 2.Suppose at this point we issue an
rollback and again
issue a nextval.What will the output
be ?
Answer: 3
• Definition
of relational DataBase by Dr.Codd
(IBM)?
Answer: A Relational Database is a
database where all data visible to the user
is organized strictly as
tables of data values and where all
database operations work on these
tables.
• What is Multi Threaded Server (MTA) ?
Answer: In a Single Threaded Architecture
(or a dedicated server configuration) the database manager
creates a separate process for each
database user.But in MTA the
database manager can assign multiple
users (multiple
user processes) to a single dispatcher (server process), a controlling process
that queues
request for work thus reducing the
databases memory requirement and
resources.
• Which are initial RDBMS, Hierarchical
& N/w database ?
Answer:
RDBMS - R system
Hierarchical - IMS
N/W - DBTG
• Difference
between Oracle 6 and Oracle 7
Answer:
ORACLE 7
ORACLE 6
Cost
based optimizer Rule based optimizer
Shared SQL Area SQL
area allocated for each user
Multi Threaded Server Single
Threaded Server
Hash
Clusters Only B-Tree indexing
Roll back Size Adjustment No
provision
Truncate command No
provision
Distributed
Database Distributed Query
Table replication
& snapshots No provision
Client/Server Tech No provision
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