DB Development

  Home  Databases Programming  DB Development


“DB Development frequently Asked Questions in various DB Development job Interviews by interviewer. Get preparation of DB Development job interview”



10 DB Development Questions And Answers

4⟩ How to create an external table?

//1st of all create a directory to store ur external table

CREATE DIRECORY EMP_DIR AS '/FLAT_FILES' ;

// now write the following line of code to create an

external table at that directory

CREATE TABLE OLDEMP(ENO NUMBER,ENAME CHAR(20),DOB DATE,)

ORGANIZATION EXTERNAL

( TYPE ORACLE_LOADER

DEFAULT DIRECTORY EMP_DIR

ACCESS PARAMETERS

(RECORDS DELIMITED BY NEWLINE

BADFILE 'BAD_EMP')

LOGFILE 'LOG_EMP'

FIELDS TERMINATED BY ','

(ENO CHAR , ENAME CHAR DOB CHAR DATE_FORMAT

DATE MASK "DD-MON-YYYY"

)

)

LOCATION ('EMP1.TXT')

)

PARALLEL 5

REJECT LIMIT 200;

 150 views

5⟩ What is the use of foreginkey?

foreginkey is use to have relation between two tables,which

requires primary key in master table and that field can be

use by child table through foregin key.

 152 views

6⟩ What is difference between primary key and unique key?

Basic difference between primary key and unique is that primary key is used to define a table in other tables for preventing data from anomalies,and unique key is used in a table to apply unifications among different values or columns of a tables and only in that table obviously.Their is no usage of unique key outward a table but primary key is often used to make relations between other tables.

 162 views

7⟩ What is the family trees and connection by clause?

On its face, the relational database management system would appear to be a very poor tool for representing and manipulating trees. This chapter is designed to accomplish the following things:

show you that a row in an SQL database can be thought of as an object

show you that a pointer from one object to another can be represented by storing an integer key in a regular database column

demonstrate the Oracle tree extensions (CONNECT BY … PRIOR)

show you how to work around the limitations of CONNECT BY with PL/SQL

The canonical example of trees in Oracle is the org chart.

create table corporate_slaves (

slave_id integer primary key,

supervisor_id references corporate_slaves,

name varchar(100)

);

insert into corporate_slaves values (1, NULL, ‘Big Boss Man’);

insert into corporate_slaves values (2, 1, ‘VP Marketing’);

insert into corporate_slaves values (3, 1, ‘VP Sales’);

insert into corporate_slaves values (4, 3, ‘Joe Sales Guy’);

insert into corporate_slaves values (5, 4, ‘Bill Sales Assistant’);

insert into corporate_slaves values (6, 1, ‘VP Engineering’);

insert into corporate_slaves values (7, 6, ‘Jane Nerd’);

insert into corporate_slaves values (8, 6, ‘Bob Nerd’);

 138 views