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Database Programming
Databases are collections of tables that maintain and display information, often collaboratively; this information can be used for interaction with an application or gaining general knowledge. Questions about database engines and modifying or using them belong in this category.
8,803 Questions
What is heuristic optimization?
Where the 'query tree' or 'algebra tree' is transformed using a set of predefined rules that will improve the queries performance. Performing the selections as early as possible to reduce load. It is a form of Query Processing.
EMC2 is the leading provider of networked Storage (computer networks hard disk storage) for Enterprise sized Companies....think Fortune 2000...
They make Data information available to the Network Computers in a Fault tolerant and Highly Available environment.
What are examples of minicomputer?
Minicomputers were developed in the 1960s and were roughly 19 inches long. A few examples are MAI Basic4, DEC PDP and VAX series, and Prime Computer Prime 50.
Sort Groups with Crystal Reports?
Crystal reports features a group sort expert. Sorting options within this group include No sort, All, Top N, Bottom N, and Top and Bottom percentages.
What are the various types of database users?
1) End User
2) Database Admin
3) Database Designer
4) System Analysts and Programmers
5) System Administrator
*Database Systems 8th Edition
A network model is actually a flexible database method of representing objects and their relationships to each other. Its graph is not restricted to a specific hierarchy. Each individual record is not restricted by a finite number of parent and child groups.
Advantage of database management system?
One advantage of having a database management system is the fact that it can store a lot of information about customers. Another advantage is the fact that businesses can easily secure these systems while they secure their other systems.
What are different types of file organizing?
There are two types of file organization associated with computer programming. The first is sequential filing where files are arranged in a sequence order in which they are written. The second file type is relative filing where files are recorded based on their consecutive numbered position which is referred to as the cell number.
What is the full form of EDVAC?
The meaning or EDVAC is Electronic Discrete Variable Automatic Computer.
Difference between database administrator and system administrator?
A System Administrator is generically responsible for all parts of the computer network, such as user accounts, computer accounts, domain trusts, email accounts, etc. The System Administrator is probably specialized in the network server operating systems and user administration. A Database Administrator would deal specifically and in depth with all aspects of one or more databases. The Database Administrator will be highly specialized with the specific database server and client software.
ER Diagram for a medical store system?
medical store system is the system in which the medicals are arranged in manner that they are kept differen recks for the different categories
How does computer help in education?
Computers have been helping people with their education for many years. Computers help people write papers properly, and neatly. It gives them access to math calculations, and access to the Internet where they can research information.
Why is naive Bayesian classification called naive?
Naive Bayesian Classification (NBC) isreferred to as naive since it makes tha assumption that each of its inputs are independent of each other, an assumption which rarely holds true, and hence the word naive. Research has however shown that even though this assumption is often false, the technique still performs well, and hence NBC is seen as a simple yet powerful tool in the world of classification and machine learning.
What is ACID test in application in database system?
The ACID model is one of the oldest and most important concepts of database theory. It sets forward four goals that every database management system must strive to achieve: atomicity, consistency, isolation and durability. No database that fails to meet any of these four goals can be considered reliable.
Let's take a moment to examine each one of these characteristics in detail: * Atomicity states that database modifications must follow an "all or nothing" rule. Each transaction is said to be "atomic." If one part of the transaction fails, the entire transaction fails. It is critical that the database management system maintain the atomic nature of transactions in spite of any DBMS, operating system or hardware failure. * Consistencystates that only valid data will be written to the database. If, for some reason, a transaction is executed that violates the database's consistency rules, the entire transaction will be rolled back and the database will be restored to a state consistent with those rules. On the other hand, if a transaction successfully executes, it will take the database from one state that is consistent with the rules to another state that is also consistent with the rules. * Isolation requires that multiple transactions occurring at the same time not impact each other's execution. For example, if Joe issues a transaction against a database at the same time that Mary issues a different transaction, both transactions should operate on the database in an isolated manner. The database should either perform Joe's entire transaction before executing Mary's or vice-versa. This prevents Joe's transaction from reading intermediate data produced as a side effect of part of Mary's transaction that will not eventually be committed to the database. Note that the isolation property does not ensure which transaction will execute first, merely that they will not interfere with each other. * Durability ensures that any transaction committed to the database will not be lost. Durability is ensured through the use of database backups and transaction logs that facilitate the restoration of committed transactions in spite of any subsequent software or hardware failures. Take a few minutes to review these characteristics and commit them to memory. If you spend any significant portion of your career working with databases, you'll see them again and again. They provide the basic building blocks of any database transaction model.
What is the difference between usability and utility?
usability is the quality of being able to provide good service.
and
utility is the state of being useful
Where are teradata headqurters?
2835 Miami Village Dr.
Miamisburg, OH 45342 (Map) Phone: 937-242-4800
Toll Free: 866-548-8348
Uses of databases in the business world?
http://www.businessintelligencelowdown.com/2007/02/top_10_largest_.html
Advantages Cost and Risk of Database Approach?
The advantages of Cost and Risk Database Approach include being personalized and specialized. It also involves conversion costs and management cost.
There are two distinct sides to being a SQL Developer. The easiest side is writing applications that are able to interface with an SQL database.
The more complicated role requires the actual development of the SQL database; designing the tables, stored procedures, views, functions, etc.
Most SQL Developers will have a foot in both camps - doing some of the database design and then writing applications to interface with it.
an ict formula is something that can caluculate a sum faster than usuall, it will work out the sum ,, and the software that is used is Microsoft excel.
Distributed and Centralized Databases Distributed data is defined as collection of logically distributed database which are connected with each other through a network. A distributed database management system is used for managing distributed database. Each side has its own database and operating system.
A centralized database has all its data on one place. As it is totally different from distributed database which has data on different places. In centralized database as all the data reside on one place so problem of bottle-neck can occur, and data availability is not efficient as in distributed database. Let me define some advantages of distributed database, it will clear the difference between centralized and distributed database.
Users can issue commands from any location to access data and it does not affect the working of database. Distributed database allows us to store one copy of data at different locations. Its advantage is that if a user wants to access data then the nearest site (location) will provide data so it takes less time.
There are multiple sites (computers) in a distributed database so if one site fails then system will not be useless, because other sites can do their job because as I earlier said that same copy of data is installed on every location. You will not find this thing in centralized database.
Any time new nodes (computers) can be added to the network without any difficulty.
Users do not know about the physical storage of data and it is known as distribution transparency, as we know that ideally, a DBMS must not show the details of where each file is stored or we can say that a DBMS should be distribution transparent.
E.F. Codd, the famous mathematician has introduce 12 rules for the relational model for databases commonly known as Codd's rules. The rules mainly define what is required for a DBMS for it to be considered relational , i.e., an RDBMS. There is also one more rule i.e Rule00 which specifies the relational model should use the relational way to manage the database. The rules and their description is as follows:- Rule 000:A RDBMS system should be capable of using its relationalfacilities (exclusively) to manage the database. Rule 1: The information rule : All information in the database is to be represented in one and only one way. This is achieved by values in column positions within rows of tables. Rule 2 : The guaranteed access rule : All data must be accessible with no ambiguity.This is achieved in the RDBMS by using the primary key concept. Rule 3: Systematic treatment of null values : The DBMS must allow each field to remain null. The null can be stored in any field of any datatype. Rule 4: Active online catalog based on the relational model : The authorized users can access the database structure by using common language i.e SQL. Rule 5: The comprehensive data sublanguage rule : The system must support at least one relational language that has simple syntax and transaction management facilities. It can be used in the application as well as in the RDBMS systems. Rule 6:The view updating rule : All views must be updatable by the system. Rule 7: High-level insert, update, and delete: The system is able to insert, update and delete operations fully. It can also perform the operations on multiple rows simultenously. Rule 8: Physical data independence : Changes to the physical storage structure must not require a change to an application based on the structure. Rule 9: Logical data independence : Changes to the logical level (tables, columns, rows, and so on) must not require a change to an application based on the structure. Rule 10: Integrity independence : All the Integrity constraints like primary key, uniques key etc must be specified separately from application programs and stored in the catalog. Rule 11: Distribution independence : The distribution of portions of the database to various locations should be invisible to users of the database. Rule 12: The nonsubversion rule : If the system provides a low-level (record-at-a-time) interface, then that interface cannot be used to subvert the system, for example, bypassing a relational security or integrity constraint. Note:- Any database management system which fulfills 6 or more than 6 rules can be considered as the RDBMS. Maulin Thaker Codd's Rule There are 13 (0 to 12) rules which were presented by Dr. E.F.Codd ,in June 1970,in ACM (Association of Computer Machinery) Rule 0. Relational Database management “A relational database management system must use only its relational capabilities to manage the information stored in the databaseâ€. Rule 1. The information rule All information in the database to be represented in one and only one way, Namely by values in column positions within rows of tables. Rule 2. Logical accessibility This rule says about the requirement of primary keys. Every individual value in the database must be logically addressable by specifying the name of table, column and the primary key value of the row. Rule 3. Representation of null values The DBMS is required to support a representation of "missing information and inapplicable information" (for example, 0 'Zero' is different from other Numbers), This type of information must be represented by the DBMS in a systematic way (For example Null Character ). Rule 4. Catalog Facilities The system is required to support an on line, in line, relational data access to authorized users by using their Query language. Rule 5. Data Languages. The system must support a least one relational language (It may support more than one relational language) that (a) has a linear syntax, (b) can be used in two ways and within application programs, (c) supports data operations security and integrity constraints, and transaction management operations (commit). Rule 6. View Updatability All views that are theoretically updatable must be updatable by the system. Rule 7. update and delete. The system must support INSERT, UPDATE, and DELETE operators. Rule 8. Physical data independence Changes to the physical level (how the data is stored, whether in arrays or linked lists etc.) must not require a change to an application based on the structure. Rule 9. Logical data independence Changes made to tables to modify any data stored in the tables must not require changes to be made to application programs. Logical data independence is more difficult to achieve than physical data independence. Rule 10. Integrity Constraints Integrity constraints must be specified separately from application programs and stored in the catalog. It must be possible to change such constraints when they are unnecessarily affecting existing applications. Rule 11. Database Distribution The RDBMS may spread across more than one system and across several networks, however the tables should appear in same manner to every user like local users. Rule 12. The Non Subversion rule If the system provides a low-level interface, then that interface cannot be used to weaken the system (e.g.) bypassing a relational security or integrity constraint.
