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What is Null Interface? What are the important in Java?
23kannan
- May 8th, 2008
Null interfaces act as markers. They just tell the compiler that the objects of this class need to be treated differently. some marker interfaces are : Serializable, Remote, Cloneable
srinivas
- Dec 24th, 2006
Null interface is a markup interface
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What is an internal schema in a database and how can a business analyst prepare an ERD?
zaneizane
- Jul 22nd, 2008
This may be considered as the mapping of the data and data relations into an indefinitely large linear address space. This specifies some or all of the data structures necessary to support the data and data relations declared in the conceptual schema.
ALOK BATHAM VAISH
- Dec 24th, 2006
THhe overall design of the database is called Scheema.
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Unique and Non-unique keys
Discuss the difference between unique and non-unique keys
mudkhedkar
- Nov 7th, 2008
Unique - Take for example employee table, it has column empno which is called as unique key where as non-unique key is column workdept, i.e when we do relationship between two tables as employee & department tables, dept. table also contains deptno as column so it is called as non-unique key.
KamalChauhan
- Jul 11th, 2008
Unique keys can have only one null value or rather i should say that every value in the column(which is marked as unique key) must be unique.
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Converting extended E-R model
Describe the process of converting an extended E-R model into a relational database design.
chaitra murthy
- Jan 16th, 2009
ER Model->Logical schema->Normalization->Creating database with tables.
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One to many
Explain the representation of a one-to-many strong entity relationship in a relational database design.
chaitra murthy
- Jan 16th, 2009
Department-Employees Under one Department many employees are working.Project-Employees
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Type of Participation
What is meant by type of participation? Name the three types of relationship participation.
chaitra murthy
- Jan 16th, 2009
I just know two types of Participation: Total and Partial.Lets take an example of 2 entities Department and Employee. Relation: For each department there is an Head of the Department (who is an emplo...
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What is Sub-schema?
Madhu Kalla
- Feb 10th, 2009
The subschema is the logical view of the data as it appears to the applications program
Dheeraj
- Aug 29th, 2006
In database management, an individual user's partial view of the database. The schema is the entire database.
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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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ILRM
IRLM is a module of DB2 which doesA. LoggingB. Thread creationsC. Concurrency controlD. Both logging and thread creation.
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Data Validation Life Cycle
Explain the lifecycle regarding validating data from start to finish?
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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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Database Design
You have been asked to design the following database diagram:“We would like to store a list of user’s in the database with their corresponding network of friends, groups, as well as any messages which are swapped between them. A user consists of a username, password, first name, last name and profile picture. A message is a string. User’s can have many friends but usually start off with none or...
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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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