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Data Redundancy
Explain what are controlled and uncontrolled data redundancy?
dhs01
- Apr 15th, 2009
I view this as planned and unplanned. Generally planned redundancy for performance reasons has some steps taken to ensure that there is syncronicity between the data. I am not sure if there are formal...
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Size of Oracle package
“Bigger the size of a Oracle package, the better”. Do you agree? Justify.
dhiren21
- Sep 20th, 2009
No - I do not agreeFunctionality depends..What are you trying to do in a package depends a lot...A Package can call Views, Functions and Triggers, Update, Insert, Delete.. Purpose of a Package, For...
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If we have a table which is accessed by multiple users and two or more user's are simultaniously trying to modify the table. Then what happens and how can we manage such situations?
dj_dj_dj
- Mar 18th, 2010
Simultaneously modification of same table by two or more users cause Oracle server to go into hang state, to avoid such a state first user who used dml statement should issue commit or rollback comand...
Gajanan
- Jul 13th, 2007
There are two ways of changing the rows in particular table.One to delete the rowSecond to modify/Change the data of row in table.In every case we opt for exclusive locks So when one user has exclusiv...
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What parameters define RDBMS?
sangam.princesalim
- Apr 8th, 2010
There are a set of rules known as Codd's rules. In all there are 13 rules. 12 were defined by Codd & the 0th rule is interpreted by Subject experts. Altough there is no Database which is fully compliant with the Codd's rules and hence we do not have a perfect / accurate RDBMS as of now.
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Data Models
Explain the three data models and examine a range of issues that are intergral to database environment such as the end user and different platforms compatibility?
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RDBMS Relation
What is the relation between the store and the customers when they shop the products at that store?
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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Defragmentation and Re-organization
What is the difference between defragmentation (coalescing) and re-organization (rebuilding, moving)?
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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Table Indexes
What is the disadvantage of creating large number of indexes on a table?
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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How to delete multiple tables at a time? e.g like c* means all the tables starts with c have to be deleted at a time.
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
- 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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Hi all...Can you please tell me how to delete the duplicate records in a table.
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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Is it possible to have primary key and foreign key in one table if yes so what is the use of foreign key?
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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What is the difference bwtween view and join
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...
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What is codd's rule?
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 Rulerajakumar_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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Difference between Data abstraction, schema and instance
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
- 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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Relationship Between Database and Data Warehouse
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
- 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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Using examples differentiate between a DBMS, RDBMS and a Distributed database
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
- 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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Entity Relationship
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
- 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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What is topdown and bottomup logical database?
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...
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