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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 are the three levels of database design?
Well, there are actually FIVE (or even SIX, according to some..) but the first three are the most commonly cited parts of normalization.
1) Identification of data and grouping in to logical units (e.g. fields and tables)
2) Establishing key values for each table
3) Analyzing relationships and eliminating non-key dependencies
A database that is in "Third Normal Form" is usually pretty correct, logically speaking.
How do you find relation between tables in a database?
There are two generic types of relationships that are found between tables in existing databases, those that are explicit (or defined) and those that are implicit (or undefined.)
The explicit relationships are defined differently in each database management system, so finding these relationships will depend on which type of database you're using. Typically they can be found via the user interface when designing one of the two tables in the relationship, viewing a relationship option, or by applying SQL against specific system tables.
The explicit relationships usually enforce referential integrity in the database, so they are strongly encouraged over implicit relationships, but still implicit relationships will be found in the real world in existing databases.
Implicit relationships are relationships where the primary key in one table can be clearly identified in another table as a foreign key, but there is no explicit relationship defined. Because the name of the foreign key matches or is similar in pattern to the the the primary key in the other table, you can imply that there should be a relationship between those tables. These relationships can be identified by foreign key names and by looking at existing SQL and queries in the database system to see what fields tables are joined on.
A complex Query is a quiery that is much more complex than a normal quiery so search up complex then quiry!!!!
What are disadvantages of database systems?
- Database systems are complex, difficult, and time-consuming to design
- Substantial hardware and software start-up costs
- Damage to database affects virtually all applications programs
- Extensive conversion costs in moving form a file-based system to a database system
- Initial training required for all programmers and users
Thank you
How do you find the greatest of three numbers in using CASE statement in sql?
Assuming you want to find the greater of 3 values that are in a table, you could do it this way: CREATE TABLE #T ( Column1 INT, Column2 INT, Column3 INT ) INSERT #T VALUES (-100, 25, 1000) INSERT #T VALUES (2, 66, 10) INSERT #T VALUES (110, 0, 200) INSERT #T VALUES (-1, -2, -3) INSERT #T VALUES (1, 2, 3) INSERT #T VALUES (3, 2, 1) INSERT #T VALUES (1, 3, 2) INSERT #T VALUES (2, 3, 3) SELECT CASE WHEN Column1 >= Column2 AND Column1 >= Column3 THEN Column1 WHEN Column2 >= Column3 AND Column2 >= Column1 THEN Column2 ELSE Column3 END AS MaxValue FROM #T DROP TABLE #T
A manual file system refers to using paper files in filing cabinets. Today, this system is not as efficient as having an online database to use in an office.
Are there any major similiarities between object oriented databases and relational databases?
In a Object Oriented Database, information is given in the form of objects as used in programming languages. "When database capabilities are combined with object programming language capabilities, the result is an object database management system (ODBMS). An ODBMS makes database objects appear as programming language objects in one or more object programming languages." (http://en.wikipedia.org/wiki/Object_database)
"A relational database is a database that conforms to the relational model, and refers to a database's data and schema (the database's structure of how those data are arranged). Common usage of the term "Relational database management system" technically refers to the software used to create a relational database, but sometimes mistakenly refers to a relational database." (http://en.wikipedia.org/wiki/Relational_database)
What are the types of database?
There are three database models. The three database models are as follows :
1) relational
2) network data
3) hierarchical
What are Interactive query facilities?
Interactive query facilities refers to management programs which make it easy to support multiple time-varying attributes at ago. These are used in database programming and ensure that reports are made with minimal data processing.Ê
Difference between classification and clustering?
Classification is a type of supervised learning (Background knowledge is known) and Clustering is a type of unsupervised learning(No such knowledge is known).
One paper-based database I can readily think of is a phone book.
Paper based database is database that consists of many papers, not a e-database!
Paper-based communicaton is anything written, drawn or printed.
What are the functions of DBA?
What is a DBA and what are their function?
What is a DBA? What does a DBA do? The term, DBA refers to the Database Administrator. A database is a collection of information that's related to a particular function or purpose. In its simplest form, your contact information kept in a file on your system is a database. We will not dwell much on databases here but it is important to understand what drives the demand for DBAs. A key requirement of modern IT infrastructure is secure and timely access to and storage of vital data. The most reliable, time-tested method of storing electronic data is inside a database.
Databases are needed by organizations that store and use information, irrespective of location or industry. And in today's knowledge-driven economy useful and timely access to information makes the difference. Why use databases is like asking why electricity is useful. Is there any industry or business that doesn't depend on information? The aim of databases is to aid the generation and the exploitation of knowledge in a reliable and cost-effective manner.
How would banks survive without databases on customers and financial transactions? E-business sites use databases to track orders and inventory. Telecom operators can't do without databases if they must keep track of accounting and subscriber information. Airlines, airports depend on databases.
The most popular database products are from Oracle, Microsoft, IBM, MySQL and Sybase. Oracle is the market leader in the database market followed by Microsoft SQL Server. And from the open source scene, MySQL is making impressive impact in the database world.
So what does a DBA do? DBAs are regarded as "those professionals who organize information in a meaningful way so it can be easily maintained, retrieved and updated". DBAs ensure that data produces and delivers real business value. The role of the database administrator is very important in an organization. Though the role can be quite complex, let us identify the core functions.
Database Implementation and Design
A critical duty of the DBA is designing databases for maximal performance, scalability, flexibility, and reliability. A well-designed and implemented database justifies the database investment. In this regard, the DBA is responsible for installing new DBMS and upgrading existing DBMS. The DBA must be conversant with installation and upgrade issues, i.e. problems, requirements, etc.
Performance Monitoring and Tuning
A DBA must make sure databases are fast and responsive. A slow response database is usually indicative of poor system performance -something is wrong somewhere. The DBA monitors the state of the database for optimal performance and the error log or event log is also monitored for database errors. Poorly tuned databases are frustrating to use - they tend to add more stress than value. Monitoring is essential to assess the state of the database and tune accordingly.
Availability, Backup and Recovery
To many in the IT industry, the most important job of the DBA is that of availability, backup and recovery of data. Because of the value placed on electronic data, the database must be protected from all forms of failure -hardware, software, and human. A DBA maintains the information an organization needs to be successful. In the DBA world, "nothing else matters if your database can't be recovered".
Availability means data must be available to all who need it when they need it. What is the use of having a great, functional database if half of the time, it is inaccessible due to one failure or the other. A database only has value when it is available. If data is not available, the business stops functioning. Imagine the impact this will have on a bank that can't have access to customers' balances. A DBA must be equipped to eliminate and reduce outages -planned and unplanned. Since not all failure can be predicted, the DBA needs to implement recovery procedures that will reduce downtime associated with failure.
User and Data Security
The DBA is responsible for security management. DBA work must be grounded in the fundamentals of IT security. Security must be designed into the database and applications. This involves assigning users to databases and determining the proper security level for each user. To make sure data is secure rigorous security schemes are required for production and test databases.
Working with Developers and Network Administrators
DBAs need to work closely with members of the technical team to ensure high, overall database performance. For instance, there is an increasing overlap between the functions of the DBA and the developer. DBAs also work with network administrators who run the servers on which their databases reside. In fact quite a few DBAs initially start out as programmers or network system administrators. DBAs and developers especially have to work as a team in areas such as design, debugging, implementing and tuning of queries, triggers and stored procedures that are stored in the DBMS. Today's databases do not just store data. They store stored procedures, triggers and user-defined functions, which are processes that act upon that data.
What have been highlighted are major functions of a DBA. It should be evident that the role of the database administrator is very important in an organization.
Success as a DBA
To succeed as a DBA, organizational skills are essential. It is a promising field for people who love planning and paying attention to details. Do you love details and planning?
Working with developers and Network administrators means you should have excellent interpersonal and communications skills. Teamwork and team building skills are essential. How do you motivate other members of the team? How do you provide leadership? DBAs maintain the information the organization needs to be successful. Do you have a clear business understanding of what the database systems are meant to achieve?
Also it helps to have an open mind. All databases and systems are not the same and there are many different ways of doing things. Often there is no single answer to a given question. There are best practices and standards you must adhere to, but you must also be creative and flexible in dealing with situations. Solving situation A may require you to think differently from the way you solved situation B. Nothing is cast in stone. There is no box of absolutes!
In addition as the DBA, you should recognize that the database is your responsibility. This requires leadership and the pursuit of excellence on your part, by being an advocate for best practices and good design. In this respect and due to the functions of DBAs in the technical team, DBAs are often involved in IT management and key aspects of Project management.
Knowledge and Certification
If your aim is to become a database administrator, you need to understand the underlying concepts of database. You need to understand concepts like Tables, Views, Queries, Primary Keys, Foreign Keys, Types of Indexes, Columns and the different data types. Then you'll need to learn concepts of tablespaces, partitions, stored procedures, packages and functions, business objects, etc.
A programming background is helpful. Any programming knowledge is highly recommended but query language knowledge (PL/SQL or MS-SQL) is a must for a DBA. You need to know how to actually talk to the database. Knowledge of Visual Basic is a definite plus.
Get books, read magazines, use Internet resources, participate in DBA related forums and news groups and start from there. Attend Formal training courses. Also visit relevant websites and talk with practicing DBAs. Look for opportunities to practice. And your interest or quest will motivate you to pursue more once you have some grasps of the basics and concepts.
While Oracle's DBA and Microsoft's MCDBA are still leaders for database certifications, MySQL Core Certification is establishing itself as a valued credential.
However, though certification is important, just like the software development community, premium is placed on work experience as a programmer or network/systems administrator first. Most DBA certifications are usually middle level to advanced level certifications. With the increasing competition for DBA opportunities, having a certification could give qualified candidates an edge.
Project management training and certifications () are also important for experienced and growing DBAs.
Other Issues
- There is a future for most in-demand IT professions, some however lend themselves faster to opportunities for newcomers than others. In that light, your knowledge choices should also depend on opportunities at your disposal. For example, investing in DBA knowledge and certification expertise could be great as a newcomer, if you already have a job as a junior database administrator. However, by the same token, while having an Oracle DBA qualification equips you with useful knowledge, you can only apply what you have acquired in an environment that has Oracle database installed, or with organizations that support Oracle installations.
- There is a rush for certification, but please get the picture clear. There is a need to strike the right balance between certification and your expectations. Certification is no substitute for experience, but it's better than nothing. But be realistic: while certification may confer advantage, it doesn't guarantee anything. You therefore need to make sure you examine opportunities for work experience as well. Can you retain what you have learned without having the opportunity to practice it? Are you just getting certified so as to have something?
- More opportunities exist for experienced DBAs or programmers than for entry level DBAs. Since DBAs are responsible for an organization's critical asset -- data -- they tend to prefer those with some degree of experience. Typically, even the junior DBA will already have some IT experience, either as a developer or as a system administrator.
- Application Developer or Database Administrator? This issue always comes up in assessing Database career options. There is a need for DBAs as well as Application Developers. It depends on where your passions lie. An application developer is more of a business analyst / software developer while the DBA as described above is more of a data facilitator - making sure data is secure, available and used productively. Click to Learn more about the differences
Future
The industry including the Database scene is moving toward more automation. For example, Oracle's latest release 10g has RAC, automated storage management, ADDM, Enterprise Manager, grid control, and many other advanced features. DBAs will have to shift focus to more business matters than just technical administration. The focus will be on how to add business value. With more and more complex systems, the creativity of the DBA is essential.
These advances in technology underline the growing and continuing need to take advantage of opportunities in the knowledge world. There is in addition, a need to eliminate the inefficiencies and increasing management and administrative costs associated with business. This existing and foreseeable demand in the database market sustains the need for DBAs. And trends indicate that DBA expertise will continue to be valuable in the years ahead.
Conclusion
Becoming a DBA involves more than getting a certification. It requires intensive study, constant learning, practice and most importantly the creation of opportunities for work experience. Furthermore, you must have the right attitude and personality to handle the tasks described earlier. Focus on what works and what matters. Have a passion for learning the DBA substance mentioned earlier and keep on learning. Have an open, enquiring mind.
There are prospects in the database field just like in any other field but it all depends on your perspective and situation. Do you have the background? Do you have the interest? What opportunities for education and experience are available to you? Can you face the challenges? The choice is yours: to DBA or not to DBA?
I wish you all the best in your IT Career,
What is the meaning of operand data type?
Operand data type is one of the two components of computer language and expressions. It is the manipulated object or the instruction that specifies which operation is to be performed.
This is an attribute that is most likely to show itself. You may have the recessive attribute, but the dominant one takes over.
Why is it important to test a database?
Many applications today rely on a backend database in order to function. If the database is not working properly, then the entire application is typically inaccessible because so much information including logins are stored in the database. Databases should be tested for boundary conditions, stress, function, and structure to ensure that everything is working as designed.
"Jumpstart" is OVID Technologies name for URLs which can be constructed and used as shortcuts to various functions and areas of the OVID Web interface. These URLs can be created and used by anyone who has access into an IP-restricted OVID subscription -- in this case UT System Libraries. This page offers brief instructions, geared specifically to UT System OVID subscriptions, on how to assemble these URLs. I found this answer at http://www.lib.utsystem.edu/about/ovid/jumpstart.html
What are field can be used as primary key?
A field or set a of fields Êin a database tableÊwith unique values Êcan be used as a primary key.ÊPrimary key field cannot have a null value.
What object must be created first when creating a database file?
To use the module, we need to create a connection object that represents the database, it needs to have a username, password, and host. Here are the steps to create a database: open Microsoft access, create a new database, save the file, and browse the new database menu.
What does it mean to start in desending order?
It means bottom to top ordering, e.g. 9,8,7,6,5,4,3,2,1 or z,y,x...
What is the difference between sap abap and sap basis admin?
ABAP is the programming language used within SAP to customize, generate forms, generate reports, etc. BASIS is the administration module of SAP, used to control code changes, upgrades, network setup, database admin, etc.
