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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 difference between data warehouse and traditional database used OLTP?
{| |+ Differences |- | Data warehouse database OLTP database Designed for analysis of business measures by categories and attributes Designed for real time business operations. Optimized for bulk loads and large, complex, unpredictable queries that access many rows per table. Optimized for a common set of transactions, usually adding or retrieving a single row at a time per table. Loaded with consistent, valid data; requires no real time validation Optimized for validation of incoming data during transactions; uses validation data tables. Supports few concurrent users relative to OLTP Supports thousands of concurrent users. |}
http://www.geekinterview.com/question_details/15800
When is database not a database?
a database is information storing system where you can store information organized. you can make table for different categories and different topic. you also can relate different type of data each other by using some unique key. ( www.databizsofware.com ) Now a days every database are based on relational database system. each table hold different yet interrelated information. they stay connected with each other by unique key.
isitak
databizsoftware.com
What might a bank use a database for?
To store detail of customers,
how much they have in the bank,
what their billing address is,
the account name,
account type,
sort code,
account number,
and more like them above.
CheckPoint Chapter 2 Programming Problem?
System-Level Requirements Example
Consider the Paint the Room program, in which you developed what are often called system-level requirements-the basis for all subsequent analysis and design steps. The following steps will take these system-level requirements and refine them into a detailed blueprint for the program.
Up to this point, you have identified the processes the program must perform, but you have not given any consideration to exactly how the processes work together to solve the problem. At this point, you must generate a description of the processing using pseudocode, a natural language description of the processing the application must perform.
The natural place to start is the system-level requirements you identified in the Input-Process-Output (IPO) chart. Determine how the processes work together: Once you have determined the top-level logic, you can then design each of the individual processes. It is this step-wise refinement process that allows you to conceptualize a vague problem into increasing levels of details in order to actually generate a working program. This point is important because the step-wise refinement pattern is used throughout the entire program development-each new piece of information is based on, and is a refinement of, the information uncovered in the previous step.
For this week's CheckPoint, you will refine the IPO table into a complete design, as demonstrated on pp. 33 and 36 of Extended Prelude to Programming: Concepts and Design (2nd ed.). Refer also to the Input and Output Process Example in Appendix B to see how more detailed analysis and design relates to the previously constructed IPO chart.
The following information demonstrates all the items you need to develop for your programming assignments and for the final project.
Analysis
Process:
1. Get user input
2. Find room area
3. Divide room area
4. Multiply gallons
5. Prompt for ounces
6. Display total
price (real: 0-100)
squareFeetPerGal (real: 0-1000)
width (real: 0-100)
length (real: 0-100)
height (real: 0-100)
Input:
Output:
total_cost (real: > 0)
Design
Main Module
Declare price as real
Declare squareFeetPerGal as real
Declare width as real
Declare length as real
Declare height as real
Declare totalArea as real
Declare gallonsNeeded as real
Declare outputPrompt as string
Declare totalCost as real
Get user input
Find room area
Divide room area
Multiply gallons
Display total
End Main Module
Input Data Module
Write, "What is the price per gallon of paint?"
Input price
Write, "How many square feet does each gallon cover?"
Input square_feet_per_gal
Write, "What is the height of the walls?"
Input height
Write, "What is the width of the walls?"
Input width
Write, "What is the length of the walls?"
Input length
End Input Data Module
Find Room Area Module
Declare sideArea as real
Declare frontBackArea as real
Declare ceilingArea as real
sideArea = 2*(length * height)
frontBackArea = 2*(width * height)
ceilingArea = width * length
totalArea = sideArea + frontBackArea + ceilingArea
End Find Room Area Module
What are roles of data administrator in database environment?
http://pkirs.utep.edu/cis4365/Tutorials/Database%20Administration/8.00700/1_multipart_xF8FF_2_tutorial.htm
Disadvantages of computerized payroll system?
The primary disadvantage of a computerized payroll system is human error. A computer is only as good as the person inputting the information.
A table is in 2NF when it is in 1NF and it includes no partial dependencies. However a table in 2NF may still have transitive dependencies, i.e., dependencies based on attributes that are not part of the primary key.
What are Problems of manual systems?
Accuracy, Ability to reliably update data and take action on trigger events Time it takes to manage the data time it takes to retrieve the data, make updates, ect. Ability to share the data. and the time it takes to share the data. As an example someone in another office needs to know something about a customer. Now they would need to call you, wastes everybodies time. The person should be able to lookup the data in the amount of time it takes to dial the phone.
What is completeness constraint?
Completeness Constraint. * The Completeness Constraint addresses the issue of whether or not an occurrence of a Supertype must also have a corresponding Subtype occurrence. * The Total Specialization Rule specifies that this is the case. This is diagrammed with a double line from the Supertype to the circle as shown here. * The Partial Specialization Rule is the one we have followed thus far in the notes (single line to the circle) -- no such constraint exists. You can have a Supertype named VEHICLE and a Subtype named AUTO, but an occurrence of a vehicle need not be an automobile.
What is a client module in DBMS?
The clients are the various apps that run on top of the DBMS-both user written apps and built in apps.Clients are also known as front ends in DBMS.For example when we use our gmail account for mailing etc. then we basically send and retrieve information from client machines of Google Database.
A functional dependency X --> Y is full functional dependency if removal of any attribute 'k' from X means that the dependency does not hold any more.
Full functional dependency is minimal in size (contain non-redundant data)
In a relation R , attribute B of R is fully functionallydependent on an attribute or set of attributes A of R , if B is functionally dependent on A, but not functionally dependent on any proper subset of A.
OR
AàB is a fully functionally dependency, if removal of any attribute X from A would result into the cancellation of dependency. i.e. (A-{X})-->B does not hold.
It's between Hotmail, Yahoo, or Gmail. Some other one might include Microsoft outlook or AOL. It is really your opinion!
PATA (Parallel ATA), IDE or EIDE, is a interface used by storage and removable disk drives. Nowadays they are replaced by SATA (Serial ATA) and PCI Express.
Find nice answer on wikipages:
http://en.wikipedia.org/wiki/Relational_database
The CPU cycle time is the time between start up and shutdown
Disadvantages of logical data modelling?
1. Database may need completely redoing if a single field in one relational table has to be changed.
2. If an ERD is resolved incorrectly then it would have to be redone.
When is the concept of weak entity used in data modelling?
A weak entity can be identified uniquely only by considering the primary key of another (owner) entity.
Was Sumeria Hierarchical or Egalitarian?
Sumeria was a hierarchical society with a clear social hierarchy. The kings and ruling elite held the highest positions of power, followed by the priests and military officials. Slavery was also prevalent, further reinforcing the hierarchical structure. However, it is important to note that there may have been some level of social mobility in Sumeria, as individuals could potentially rise through the ranks based on their abilities or achievements.
Difference between relation and relational schema?
In database design a RELATION is the relationship that you build between two or more tables.
As an example lets say you have a Customer table. In this table you have lots of fields
FirstName, LastName, Address, City, State, PostalCode, StatusID; etc.......
Now StatusID is going to be a numeric value. Lets say that the value is 1
Now you will have a Status Table with multiple fields (ex)
StatusID, StatusName, Active, etc.....
Now when you display customer information you will not want to show a StatusID as nobody will know what this is. You will want to show the NAME associated with the status. To do this you will create a releationship between StatusID in the Customer table and StatusID in the Status table. In doing so you will provide for faster lookup results, a constraint that does not permit a numeric value in the StatusID field in the customer table that is NOT in the StatusID field of the Status table.
THEN... To show correct Results you would write a query something like:
SELECT FirstName, LastName, Address, City, State, PostalCode, StatusName
FROM Customers as c
JOIN Status as s on s.StatusID = c.StatusID
A relational Schema is simply a representation of your database highlighting the relationships that you have created throughout.
