OCI (Oracle Call Interface)

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7 OCI (Oracle Call Interface) Questions And Answers

2⟩ What is difference between SQL Server and Oracle?

ORACLE and SQLSERVER BOTH RDMS.oracle supports 11+1/2

E.F.codd rules out of 12 rules.but remaining rdms supports

only 5 rules.compare with sqlserver ,oracle has more secure

and high performance to retrieval the data from database.

but sql server supports only microsoft operating systems.

oracle can support every operating system.

using oracle pl/sql ,we can send block of queries to

oracleserver at a time.but IN sqlserver we can not send

multiple queries at a time to the server.

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3⟩ What is database normalization?

Normalization means the process in which raw data is

converted to filtered data.

Types of Normalization are:- 1NF,2NF,3NF.

1NF:- Table that contains one or more repeating groups

Identify and remove repeating groups.

2NF:-Describes a table that is fully functionally dependent

Full functional dependency – means that if B is

functionally dependent on A but not on any proper subset of

A, it is fully functionally dependent on A

Partial dependency – is if there are some attributes from A

that can be removed and the dependency still holds

3NF:- In 3NF we remove the transitive dependencies.

Transitive dependency – A->B and B->C implies that A->C

C is transitionally dependent on A through B

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4⟩ What is the main difference between foreign key and primary key?

primary key:- A primary contains unique and notnull.it means

a primary key column does not contain null values and

duplicates.A table containe only one primary key.using this

we can access the data from table easily.

foreign key:-a fk can contain duplicate values but it not

contain null values.using fk to establish relationship

between two tables. a parent table primary key should be

referenced by child table primary key.

one fk should be referenced by only one primary key the main difference between two keys is

pk is used to access the data from table.

fk is used to establish the relationship between two tables.

pk does not allowed duplicate and null values.

fk can allows duplicate values and does not allowed null

values

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5⟩ Tell me in function why return single value?

FUNCTION HAVING SINGLE RETURN PARAMEATER.IT IS USED FOR

CALICULATION PURPOSE.

EX: CRETE OR REPLACE FUNCTION [PARAMEATER] RETURN TYPE;

BEGIN

RETURN PARAMEATER;

END;

BUT FUNCTIONS RETURN MORE THAN ONE VALUES ALSO,BY USING

RECORD TYPES.

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6⟩ Can we use a having clause in groupby clause?

having cluase can only be used with group by clause.

if there are 500 records i will give rownumber<250 then it

fetch 249 records.

NVL2( string1, value_if_NOT_null, value_if_null )

if string1 is not null then it returns 'value_if_NOT_null'

and if string1 is null then it returns 'value_if_null'.

if there are four tables without using cartesian we have n-

1 join where n is number of tables. i.e 4-1=3 join required

four tables without using cartesian.

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