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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
Why are databases used in the library?
Database is used so that people can be able to access e-books, journals using Databases such as Ebcohost, Online Public Access Catalog (OPAC).
Architecture diagram for the project of airline reservation?
There are five essential elements to the most basic construction of an airline reservation. Virtually all CRS (Computer Reservation Systems) or GDS (Global Distribution Systems) are based upon a similar architecture. (although some have now chosen to ignore one element due to it not being used effectively by individuals using the systems).
The first element is the Itinerary:
From where is the passenger departing and what is their destination? How many passengers will there be? When do they wish to travel -And- when (if) are they returning.
The second element is the Name of the passenger(s). Surname/First name/Title (SHK, LDY,LRD,HRH,REV,CAPT, MSTR, MR,MRS,MISS, DR., etc.
The third element is the Phone Contact details. How is the airline or travel agent to contact the passenger should there be a delay in the flight. What is the Home number, the Work Number, or Mobile number and even possibly the hotel number where the passenger is staying: CTCH, CTCB, CTCM,CTCH
The fourth element is the Ticketing information. When will the passenger call for the ticket (TAW/22JUN), has it already been ticketed (T./), must it be ticketed by a certain date (TTL/22JUN), etc.
The last essential element to the architecture is called the 'Received' Field. (R.) Essentially, you're documenting who, precisely was it who instructed you to charge £5,000 to their credit card. Was it the passenger to whom you were speaking, was it the passenger's secretary, was it the wife, or even possibly the girlfriend.
At the launch of airline reservation systems, they were creatively designed to address virtually every contingency, permitting a cross-section of cultures and languages to effectively communicate without the necessity of learning different languages. The language used demanded precise adherence and time after time, it proved itself.
In fact, airline staff beginning careers in the airline's reservation departments were not permitted to have pens, pencils, or sheets of paper. The reservation system before them was so well designed, under not only the guidance of individual international airlines, but NATO, MOD, and CIA input was used as well.
Unfortunately, when the airline systems were first introduced to travel agencies as a work tool, the airlines were no longer able to effectively enforce college-educated staff utilising the data systems correctly and due to the appalling number of errors being made by travel agents, leaving the airlines to try and sort out thousands of miles down-line, quick steps had to be taken to 'dumb down' the booking process for the agent community. In many cases, it still presented so many problems that some airlines simply refused to let blocks of agencies have access to their reservation systems. This was the launch point for commercial CRS systems sold or leased to retail travel agencies.
Teaching the travel agents required simple tools to help staff cope with the complexities of making an airline booking. The initial architecture presented the acronym PRINT.
P = The Phone Number of the passenger
R = Who told you to make this booking, cancel the booking, change it., etc.
I = The itinerary. Where is the passenger going?
N = What is the name of the passenger (s)
T = When must the ticket be issued.
Virtually anything else beyond the above were considered ancillary elements to the basic architecture. For example: Imperative statements or SSR's (Special Service Requests) were specific instructions entered into the computer, telling the airline to do something that required action: Ordering a meal, wheelchair, etc. And Non-imperatives, or 'other service information' (OSI), provided non-actionable information that the airline would not see until the passenger is checking in for the flight.... Sample OSI's include: DEAF - passenger is deaf, TCP4 TW 2.Jones/George/Carla - this booking is to complete a part of 4 travelling together, the passenger on this PNR (passenger name record) is travelling with George and Carla Jones. OSI JFK CTCH 212 759 3000 - Plaza Hotel = passenger when in New York is staying at the Plaza Hotel. OSI GIG CTCH - 74 55 2933 - Copacabana = whilst in Rio passenger is staying at the Copacabana Hotel.
What are the advantages of specialty-line wholesalers?
Specialty-line wholesalers carry the most narrow product assortment, usually consisting of a single product line or part of one. Because specialty-line wholesalers are product experts, they can offer extensive sales and product support.
Can you write a program in DBMS like C?
DBMS means Data Base Management System, it is not a programming language.
What secondary type of data is used in econometric models?
Economic forecasting models predominantly use time-series data, where the values of the variables change over time.
What is the description of the relationship between two data sets?
the realationship would be between pont a and b meaning its the galaxy of the numerical pie graph to the ^2nd power - the expotinatal growth of the economy itself, also its the quest of the square root- the quadratic formula of the equinox formula. The formula will then be used to write out the 5 base numbers in the standard deviation within the 5 numbers classified above. But overall I would say the question is the description between two data sets.
It is nothng but the information about information in database.... Is called metadata
Is there an example of data processing cycle related to human activities?
computing a grade and salary
What are the advantages for encoding data on bacodes?
Fast, quick, precise, reliable, less space, fast, easy peasy lemon squeezy
What are the classifications of computer according to data handled?
analog computer, digital computer, hybrid computer
Discuss different types of production systems?
It is very important for businesses to identify the processes that add value, so that they can enhance these processes to the ongoing benefit of the business.
There are three main types of process: job, batch process and flow production.
Job production
Job or 'make complete' production is the creation of single items by either one operative or a team of operatives e.g. the Humber Bridge or a frigate for the navy.
It is possible for a number of identical units to be produced in parallel under job production, e.g. several frigates of a similar type. Smaller projects can also be seen as a form of job production, e.g. hand knitting a sweater, writing a book, rewiring a house, etc.
Job production is unique in the fact that the project is considered to be a single operation, which requires the complete attention of the operative before he or she passes on to the next job.
The benefits of job production are:
1. The job is a unique product, which exactly matches the requirements of the customer, often from as early as the design stage. It will therefore tend to be specific to a customer's order and not in anticipation of a sale. For example, someone doing a customised spray paint job on a motorcycle will first discuss with a customer the sort of design he would like. A detailed sketch would then be produced on a piece of paper. Once the sketch has been approved the back of the sketch will be chalked over and traced on to the relevant piece of the motorbike. The background work is then sprayed on with an airbrush before the fine detail is painted on. The finished work is then inspected by the customer who will pay for a unique product.
2. As the work is concentrated on a specific unit, supervision and inspection of work are relatively simple.
3. Specifications for the job can change during the course of production depending upon the customer's inspection to meet his or her changing needs. For example, when a printing firm like Polestar is asked to produce a catalogue for a grocery chain it is relatively simple to change the prices of some of the goods listed in the catalogue.
4. Working on a single unit job, coping with a variety of tasks and being part of a small team working towards the same aim would provide employees with a greater level of satisfaction. For example, aircrews working for United Airways would treat each flight as a specific job, with passengers requiring individual attention to their specific needs - e.g. for vegetarian dishes, wheelchair access to the flight, etc.
Batch production
The term batch refers to a specific group of components, which go through a production process together. As one batch finishes, the next one starts.
For example on Monday, Machine A produces a type 1 engine part, on Tuesday it produces a type 2 engine part, on Wednesday a type 3 and so on. All engine parts will then go forward to the final assembly of different categories of engine parts.
Batches are continually processed through each machine before moving on to the next operation. This method is sometimes referred to as 'intermittent' production as different job types are held as work in progress between the various stages of production.
The benefits of batch production are:
- It is particularly suitable for a wide range of almost similar goods, which can use the same machinery on different settings. For example batches of letters can be sent out to customers of an insurance company.
- It economises upon the range of machinery needed and reduces the need for a flexible workforce.
- Units can respond quickly to customer orders by moving buffer stocks of work-in-progress or partly completed products through the final production stages.
- It makes possible economies of scale in techniques of production, bulk purchasing and areas of organisation.
- It makes costing easy and provides a better information service for management.
Flow production
Batch production is described as 'intermittent' production and is characterised by irregularity. If the rest period in batch production disappeared it would then become flow production. Flow production is therefore a continuous process of parts and sub-assemblies passing on from one stage to another until completion.
Units are worked upon in each operation and then passed straight on to the next work stage without waiting for the batch to be completed. To make sure that the production line can work smoothly each operation must be of standard lengths and there should be no movements or leakages from the line, i.e. hold-ups to work-in-progress.
For flow production to be successful there needs to be a continuity of demand. If demand varied, this could lead to a constant overstocking of finished goods.
Although with modern robotics it is possible to create variations in products being produced through continuous flow techniques, typically such products will be relatively standardized.
Achieving a smooth flow of production requires considerable pre-production planning to make sure that raw materials are purchased and delivered just-in-time, that sufficient labour is employed and that there is continuous attention to quality throughout the production process.
The benefits of flow production are:
control is easy.
Production process
The production process is concerned with transforming a range of inputs into those outputs that are required by the market.
This involves two main sets of resources - the transforming resources, and the transformed resources.
The transforming resources include the buildings, machinery, computers, and people that carry out the transforming processes. The transformed resources are the raw materials and components that are transformed into end products.
Any production process involves a series of links in a production chain. At each stage value is added in the course of production. Adding value involves making a product more desirable to a consumer so that they will pay more for it. Adding value therefore is not just about manufacturing, but includes the marketing process including advertising, promotion and distribution that make the final product more desirable.
The only disadvantage is when the database creater is less than professional in how the database is set up. If you use a numeric as the unique identifier for the database then the database can quickly become both useful and huge.
WHAT relational algebra operators can be applied to pair of tables that are not union compatible?
SELECT, PROJECT, DIVIDE, PRODUCT, and JOIN
no, I don't
c program for shortest remaining time scheduling algo
The two major commercial classes of database are; relational and non-relational.
Example of non-relational databases include Informix c-isam and dbisam.
The main relational databases are; MS SQL Server, Sybase, Oracle, Progress, mySQL.
Example of round robin scheduling?
example on round robin problem in OS:
let here p1,p2,p3,p4 are some process and its burst time is given as:
P1=6
P2=8
P3=2
P4=4
time quantum=4 millisec
PROCESSES P1 P2 P3 P4 P1 P2
CPU CYCLES 0 4 8 10 14 16 20
SO in this example, a process cannot exceed more than 4 millisec. so each process is not exceeding more than 4 millisec. as p1 starting time is 0 ms and ending time is 4 ms then another process started at this time which also complete 4 cycles then another process p3 start which need only 2 cycles to complete its execution ,so goes only 2 cycles and finish its execution at time 14 and p4 complete its execution at 14 . now dis process will again started until all the process does not complete its execution remaining in the time quantum limit.
What are the advantages and disadvantages to the distributed DHCP infrastructure?
Advantages:
Clients have ready access to their DHCP servers.
All client/server traffic is local.
There is no worry about DHCP traffic adding to the burden of routers.
How logical architecture of DBMS differs from physical architecture?
Architecture is the frame work of the Database Management System. They are simply classified into logical and physical.
Advantages and disadvantages in English table service?
Advantage:it teaches children new and good table manners
disadvantage:it is costly
by:stephanie nwafor
What are the disadvantages of manual library system?
Boom Boom Pow get down on the ground for me now!
What is difference between telecom and datacom?
In generic terms, Telecom is communication of voice from the sender to receiver with the help of hardware and softwares.
Datacom, is transfer of non voice (ie, data) from the sender to receiver with the help of hardware and software
1.) Discrete: restricted to integers; ordinal subjective
What is relational algebra in DBMS explain with suitable example?
Relational algebra
In order to implement a DBMS, there must exist a set of rules which state how the database system will behave. For instance, somewhere in the DBMS must be a set of statements which indicate than when someone inserts data into a row of a relation, it has the effect which the user expects. One way to specify this is to use words to write an `essay' as to how the DBMS will operate, but words tend to be imprecise and open to interpretation. Instead, relational databases are more usually defined using Relational Algebra.
Relational Algebra is :
- the formal description of how a relational database operates
- an interface to the data stored in the database itself
- the mathematics which underpin SQL operations
Operators in relational algebra are not necessarily the same as SQL operators, even if they have the same name. For example, the SELECT statement exists in SQL, and also exists in relational algebra. These two uses of SELECT are not the same. The DBMS must take whatever SQL statements the user types in and translate them into relational algebra operations before applying them to the database.
Terminology- Relation - a set of tuples.
- Tuple - a collection of attributes which describe some real world entity.
- Attribute - a real world role played by a named domain.
- Domain - a set of atomic values.
- Set - a mathematical definition for a collection of objects which contains no duplicates.
- INSERT - provides a list of attribute values for a new tuple in a relation. This operator is the same as SQL.
- DELETE - provides a condition on the attributes of a relation to determine which tuple(s) to remove from the relation. This operator is the same as SQL.
- MODIFY - changes the values of one or more attributes in one or more tuples of a relation, as identified by a condition operating on the attributes of the relation. This is equivalent to SQL UPDATE.
- Mathematical set theory based relations:
UNION, INTERSECTION, DIFFERENCE, and CARTESIAN PRODUCT.
- Special database operations:
SELECT (not the same as SQL SELECT), PROJECT, and JOIN.
For example, find all employees born after 1st Jan 1950: SELECTdob '01/JAN/1950'(employee)
Relational PROJECTThe PROJECT operation is used to select a subset of the attributes of a relation by specifying the names of the required attributes.For example, to get a list of all employees surnames and employee numbers: PROJECTsurname,empno(employee)
SELECT and PROJECTSELECT and PROJECT can be combined together. For example, to get a list of employee numbers for employees in department number 1:Figure : Mapping select and project Set Operations - semanticsConsider two relations R and S.- UNION of R and S
the union of two relations is a relation that includes all the tuples that are either in R or in S or in both R and S. Duplicate tuples are eliminated.
- INTERSECTION of R and S
the intersection of R and S is a relation that includes all tuples that are both in R and S.
- DIFFERENCE of R and S
the difference of R and S is the relation that contains all the tuples that are in R but that are not in S.
- they have the same number of attributes
- the domain of each attribute in column order is the same in both R and S.
It combines the tuples of one relation with all the tuples of the other relation.
CARTESIAN PRODUCT exampleFigure : CARTESIAN PRODUCT JOIN OperatorJOIN is used to combine related tuples from two relations:- In its simplest form the JOIN operator is just the cross product of the two relations.
- As the join becomes more complex, tuples are removed within the cross product to make the result of the join more meaningful.
- JOIN allows you to evaluate a join condition between the attributes of the relations on which the join is undertaken.
The notation used is R JOINjoin condition S
JOIN ExampleFigure : JOIN Natural JoinInvariably the JOIN involves an equality test, and thus is often described as an equi-join. Such joins result in two attributes in the resulting relation having exactly the same value. A `natural join' will remove the duplicate attribute(s).- In most systems a natural join will require that the attributes have the same name to identify the attribute(s) to be used in the join. This may require a renaming mechanism.
- If you do use natural joins make sure that the relations do not have two attributes with the same name by accident.
There are three forms of the outer join, depending on which data is to be kept.
- LEFT OUTER JOIN - keep data from the left-hand table
- RIGHT OUTER JOIN - keep data from the right-hand table
- FULL OUTER JOIN - keep data from both tables
