Hi, I recently tried to get employee names and their dept names without a join condition, this query, although succeeds, I can't figure how it works. please help.

select ename,(select dname from dept where deptno=e.deptno) from emp e;

Mark Haynes

 Profile Answers by Mark Haynes Questions by Mark Haynes

• Apr 11th, 2012

Youre using a Sub-query -- [(select dname from dept where deptno = e.deptno)] -- to get around using a join clause like -- [FROM EMP E INNER JOIN DEPT D ON (D.DEPTNO = E.DEPTNO)] -- however, you are n...

Blaster_Ayub_Khan

• Apr 10th, 2012

SQL coins the term query as the name for its commands. Basically, all SQL code is written in the form of a query statement and then executed against a database. All SQL queries perform some type of da...

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List the rules used to enforce table level integrity.

Sandhya.Kishan

 Profile Answers by Sandhya.Kishan Questions by Sandhya.Kishan

• Apr 5th, 2012

There are 3 rules to enforce table level integrity. 1.Foreign key value can be modified only if we want to match the corresponding primary key value. 2.We cannot delete records either from parent or c...

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Functions for error trapping are contained in which section of a PL/SQL block?

Sandhya.Kishan

 Profile Answers by Sandhya.Kishan Questions by Sandhya.Kishan

• Apr 5th, 2012

The Exception section of the PL/SQL block contains the functions for error handling.

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Name three activities involved in requirement gathering

Sandhya.Kishan

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• Apr 5th, 2012

Three activities involved in requirement gathering are
1.Eliciting requirement
2.Analyzing requirement
3.Recording requirement

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Which types of trigger can be fired on DDL operation?
A. Instead of triggerB. DML triggerC. System triggerD. DDL trigger

Sandhya.Kishan

 Profile Answers by Sandhya.Kishan Questions by Sandhya.Kishan

• Apr 5th, 2012

The trigger which can be fired on DDL operator is DDL trigger.

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Fakruddin Khan

• Mar 30th, 2012

The top-down method starts from the general and moves to the specific. Basically, you start with a general idea of what is needed for the system and then ask the end-users what data they need to stor...

chaitra murthy

 Profile Answers by chaitra murthy Questions by chaitra murthy

• Jan 28th, 2009

Top Down approach:- ER ModellingBottom Up approach:- Normalization

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raman sharma

• Mar 2nd, 2012

There are two type of join

1)inner join
inner join have a three type
I)equi join
II)nonequi join
III)self join

and outer join have a two type

I)right outer join
II)left outer join

and one is a ANSI join that a advance

Pradeep

• Feb 21st, 2012

Join, Inner join, Outer join, Left join, Right join, Full join

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Explain a one-to-many strong vs. one-to-many weak entity relationship.

raman sharma

• Mar 2nd, 2012

Entity relationship when attribute are connected to entity there are different different type attribute are available weak entity and strong entity when we are using key that called strong entity and when key are not connected that called weak entity

Lokesh M

 Profile Answers by Lokesh M Questions by Lokesh M

• Nov 20th, 2011

Weak Entity generally don't possess key attributes of their own whereas a Strong Entity possess its own key attributes that are independent of other entities. Weak entity is usually existence-dependent on another entity type and does not have enough attributes to form its own primary key.

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Been given this question from my son and he has told me that he googled the question but got no satisfactory answer. Would much appreciate an answer.

raman sharma

• Mar 2nd, 2012

DBMS is a when data are not stored in table and RDBMS is used to all data are stored in table and distributed database when more than one table are connected with each other so its is called a distributed database

suji

 Profile Answers by suji Questions by suji

• Dec 21st, 2011

DBMS - Its a software package combination of various computer programs which can be used to control, administer, maintain and use of the database. RDBMS - Its a database management system (DBMS) b...

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raman sharma

• Mar 2nd, 2012

normal are of five type 1) 1 normal form 2) 2 normal form 3) 3 normal form 4) 4 normal form 5) 5 normal form all normal are created to connected a table with each other and data are retrieve very ea...

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What is the relationship between a company's databases and its data warehouse?

Hirru

• Feb 10th, 2012

Database is a structured collection of relational data. Database is used to store the relational, network or hierarchical data. It contains some sort of data and it is being used by the organization...

Lokesh M

 Profile Answers by Lokesh M Questions by Lokesh M

• Nov 20th, 2011

In simple words, a database is used to store information, and a data warehouse is used to query and analyse the stored data in several ways. Data warehouse helps business management to take important...

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Difference between the three levels of data abstraction, and between a schema and instances.. Consider a two dimensional integer array of size n*m that is to be used in your favorite programming language. Using the array as an example, illustrate the difference (a) between the three levels of data abstraction, and (b) between a schema and instances.

Lokesh M

 Profile Answers by Lokesh M Questions by Lokesh M

• Nov 20th, 2011

Data Abstraction means suppression of information / details of data organization and storage. Data Abstraction gives importance to mainly essential aspects in order to help better understanding of th...

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nishant s mevawala

• Aug 30th, 2011

1.Information Rule
2.Guaranteed Access Rule
3.Systematic Treatment of Nulls Rule
4.Active On-line catalog based on the relational model
5.Comprehensive Data Sub-language Rule

rajakumar_na

 Profile Answers by rajakumar_na Questions by rajakumar_na

• Nov 14th, 2007

Dr. E.F. Codd, an IBM researcher, first developed the relational data model in 1970. In 1985, Dr. Codd published a list of 12 rules that concisely define an ideal relational database, which have provi...

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NOTNULL

 Profile Answers by NOTNULL Questions by NOTNULL

• May 18th, 2009

View is mainly created to provide security for the data and data definitions. Mainly used to retrieve the data in a secure manner.View cannot use space in the physical memory means virtually it w...

rajakumar_na

 Profile Answers by rajakumar_na Questions by rajakumar_na

• Nov 14th, 2007

One more point isView is a Schema ObjectJoin is not a schema object

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rubin2008

 Profile Answers by rubin2008 Questions by rubin2008

• Jan 31st, 2010

Yes it is possible to have primary key and foreign key in one table.For e.g the schema for table category is as followsCategory_id: int primary keyCategory_title: varchar(30)parent_id: int(3)In the ab...

Shri

• Nov 1st, 2007

Dear Vivek,If I understand your question well, you mean to say that "is there any possibility to have both?primary & foreign keys in the same table".Well, the answer is No. The foreign key (by defini...

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shibraj

 Profile Answers by shibraj Questions by shibraj

• Jan 23rd, 2008

find the rowid for the duplicate row and delete the max id no keeping the min id. thats it...

sowmya

• Nov 19th, 2007

Here != works bcoz the inner query returns only a single value. NOT IN is used when multiples values are returned by the inner query

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anand.managoli

 Profile Answers by anand.managoli Questions by anand.managoli

• Nov 26th, 2010

As per my knowledge we cannot use Regular Expressions with drop stmt. You can delete multiple tables in a single statement by separating them with a comma.Ex:mysql> show tables;+--------------...

dinu_26

 Profile Answers by dinu_26 Questions by dinu_26

• Nov 12th, 2008

There is no way to delete multiple table at a time.You can just drop a single table at a time.Syntax: table name.

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What is the disadvantage of creating large number of indexes on a table?

trupti11

 Profile Answers by trupti11 Questions by trupti11

• Nov 15th, 2010

There are a couple of reasons that I can think of for this:(1)  The indexes that are created on a table occupy physical disc space, the more the number of indexes created, the more would be the s...

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What is the difference between defragmentation (coalescing) and re-organization (rebuilding, moving)?

Mwanamume

 Profile Answers by Mwanamume Questions by Mwanamume

• Jun 21st, 2010

Defragmentation is to make data take a small space in storing (to compress data) while re-og=rganization is to rebuild or rearrange the data

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What is the relation between the store and the customers when they shop the products at that store?

vasirev

 Profile Answers by vasirev Questions by vasirev

• Jun 15th, 2010

The store table and the customer table would not have any direct relation. Instead, both of them would be pointing to a transaction table which would contain the store id and the customer id.

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