Interview Questions Answers in DB Development, DB Administration, SQL PLSQL

Questions / { ramesh }

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Answers / { ramesh }

What are cursors? Explain different types of cursors?

Answer

Implicit Cursors --Occurs on behalf of every sql statement
Explicit Cursors --Named Cursors used in Plsql
Paramaeteried Cursors --Pass Paramters to a Named Cursor

Cheers,
Ramesh

Is This Answer Correct ?

17 Yes

6 No

Question { SQL Star, 9152 }

How do you implement one-to-one, one-to-many and many-to-
many relationships while designing tables?

Answer

One to one
Parent Entity does have one Corresponding record in Child
Entity

ex : Employee and his CV

One to many

Parent Entity does have many Corresponding records in Child
Entity

ex : Employee and his Projects

many to many

Parent Entity records do have many Corresponding records in
Child Entity vice versa

ex : Employees and Employers
Employees Receive Calls from Many Employers
Employers Receive CVs from Many Employees

Is This Answer Correct ?

12 Yes

6 No

Question { IAS, 137432 }

Define candidate key, alternate key, composite key?

Answer

A composite Key can be either Primay or Unique Key
More then One Key columns are said to be composite keys

Candidate Key(Primary Key) is a Key which Maintains the Row
Uniue .Can be defined based on the Entity

Alternate Key or Unique Key is similar to PK ,except it
accepts null Values .So that the records can still be
entered submitting null values to this attribute.

Is This Answer Correct ?

151 Yes

207 No

Question { 7416 }

What is bit datatype and what's the information that can be
stored inside a bit column?

Answer

Float
Binary Data

Is This Answer Correct ?

3 Yes

3 No

Question { 10480 }

Give two examples of how you might determine the structure
of the table DEPT.

Answer

From Scott Schema

1.Desc Dept

2.Select Table_name,Column_name,Data_type,nullable from
user_tab_columns wheRE table_name = 'DEPT'

Is This Answer Correct ?

12 Yes

0 No

Question { 13658 }

Compare and contrast TRUNCATE and DELETE for a table.

Answer

Truncate is to delete the entire data of any table .does not
have criteria deletion
where as Delete can do that job
However Deleted blocks still persists and have to be
shrinked .otherwisem You still feel the Deleted Recs while
you Query Against

Is This Answer Correct ?

1 Yes

0 No

Question { 10457 }

Name a tablespace automatically created when you create a
database.

Answer

System Tablespace is Created when a New oracle Database is
created.
It,s Not-> while Creation of Tablespace
However ,Ensure No user objects created in System Tablespace

Cheers,
Ramesh

Is This Answer Correct ?

6 Yes

0 No

Question { 7598 }

When creating a user, what permissions must you grant to
allow them to connect to the database?

Answer

Grant Create session to

Is This Answer Correct ?

10 Yes

2 No

Question { 7418 }

What view would you use to look at the size of a data file?

Answer

v$datafile and v$tablespace Views

select v.FILE#,t.NAME,v.TS#,v.BLOCKS,v.BLOCK_SIZE from
v$datafile d,v$tablespace t where v.v.TS# =t.TS#

Cheers,
Ramesh

Is This Answer Correct ?

4 Yes

0 No

Question { 11620 }

How can you rebuild an index?

Answer

ALTER INDEX REBUILD ONLINE;

one Should Configure a script to Rebuild indexes at Regular
intervals for the needy

Is This Answer Correct ?

10 Yes

2 No

Question { 6342 }

Explain what partitioning is and what its benefit is.

Answer

And the Advantage are
1.Maintaincace :-Can Take Partioned tables's tablespace
offline for recovery
while other partitions are still avialable to users
Hence the Avialability

2.Performace :As the Objects are plcaed in Diffrent
Tablespaces of Diffrent Servers/locations

Is This Answer Correct ?

2 Yes

0 No

Question { 18844 }

What is the difference between the SQL Loader and IMPORT
utilities?

Answer

SQL Loader and IMPORT are ORACLE utilities

SQL Loader is used to Load the Data from Delimiter Seperted
files and files with fixed and Vaariable width Text
One can also use plsql functions and procedures to load
desired foramtted data

Import is the Utility that can only tool that understands
Oracle Export Utility used to manke logical backup against
Database/Schemas

Is This Answer Correct ?

10 Yes

2 No

Question { 13106 }

Name two files used for network connection to a database.

Answer

tnsnames.ora , listner.ora and sqlnet,ora

Cheers,
Ramesh

Is This Answer Correct ?

9 Yes

1 No

Question { Wipro, 56502 }

Can we use more than one null value for unique key?

Answer

Yes,We should .That's the significance of Unique Key

If you insert data into Unique Key column it checks for the
uniqueness of THIS NON NULL UNIQUE COLUMNAR DATA

Is This Answer Correct ?

13 Yes

15 No