In the system design process, the primary objective is to identify user requirements and to build a system that satisfies these requirements. Design of system is largely the logical design. The logical design can be sketched on a paper or on a computer terminal. The design, also including the physical design elements, describes the data [...]
Continue reading → Equijoins are also commonly known as simple joins, or inner joins. Given two or more tables, an equijoin will return the results of these tables where a common column between any given pair of tables has the same value (an equal value). Equijoins are typically joins between foreign keys in one table to a primary [...]
Continue reading → So far, we have been dealing with only one table at a time in our SQL query examples. But typically the information needed to satisfy a user query requires more than one table. In new SQL 1999, you can not only join two or more tables in a number of different ways, but can also [...]
Continue reading → System Analyst has the following duties to perform : Estimate personnel requirements, cost and time for system’s implementation. Review and approve proposed system’s solutions Perform resource planning and scheduling for system’s personnel. Develop, implement and enforce procedural standards for performing tasks of system analysis and design. Evaluate performance of system’s personnel and report on personnel [...]
Continue reading → A Linux shell is the program which interprets what you type on the command line and decides what to do with that. A shell can be invoked in a non-interactive way, for example to execute a pre-typed list of commands contained in a text file (a “shell script”). Think of a shell as the equivalent [...]
Continue reading → In Linux, if a program crashes, it often dumps a “core ” into your home directory. This is accompanied by an appropriate message. A core is a memory image and is a debugging tool. If you are a user who does not intend to debug the program, you may simply delete the core : Rm [...]
Continue reading → Sometimes, a simple GROUP BY clause just isn’t enough in a query. Once you generate a report of, let’s say, average salary by department or the standard deviation of sick days by job title, you often must run a second query that calculates the average salary or standard deviation across the entire set of employees. [...]
Continue reading → Over the past four decades the computer industry has experienced four generations of development, physically marked by the rapid changing of building blocks from relays and vacuum tubes (1940-1950s) to discrete diodes and transistors (1950-1960s), to small- and medium-scale integrated (SSI/MSI) circuits (1960-1970s), and to large- and very-large-scale integrated (LSI/VLSI) devices (1970s and beyond). Computer [...]
Continue reading → Data mining has many and varied fields of application some of which are listed below. Retail/Marketing 1. Identify buying patterns from customers 2. Find associations among customer demographic characteristics 3. Predict response to mailing campaigns 4. Markets analysis Banking 1. Detect patterns of fraudulent credit card use 2. Identify ‘loyal’ customers 3. Predict customers likely [...]
Continue reading → 1.Growing Data Volume The main reason for necessity of automated computer systems for intelligent data analysis is the enormous volume of existing and newly appearing data that require processing. The amount of data accumulated each day by various business, scientific,and governmental organizations around the world is daunting. 2. Limitations of Human Analysis Two other problems [...]
Continue reading → There are many data mining systems available or being developed. Some are specialized systems dedicated to a given data source or are confined to limited data mining functionalities, other are more versatile and comprehensive. 1. Classification according to the type of data source mined: this classification categorizes data mining systems according to the type of [...]
Continue reading → The kinds of patterns that can be discovered depend upon the data mining tasks employed. By and large, there are two types of data mining tasks: descriptive data mining tasks that describe the general properties of the existing data, and predictive data mining tasks that attempt to do predictions based on inference on available data. [...]
Continue reading → In principle, data mining is not specific to one type of media or data. Data mining should be applicable to any kind of information respiratory. However, algorithms and approaches may differ when applied to different types of data. Indeed, the challenges presented by different types of data very significantly. Data mining is being put into [...]
Continue reading → OEM automatically alert the DBA, through an e-mail message or page, to error conditions or conditions that may signal an impending error. Using OEM’s Event Manager, accessible as one of the nodes in the OEM Navigator pane, the DBA can monitor a variety of error conditions, such as an abnormal termination of the Oracle instance [...]
Continue reading → The alert log file grows in size slowly but without limit. After a few weeks, it can become cumbersome to review the file, so it’s a good idea to archive or delete the file on a periodic basis. The alert log file can be safely renamed or deleted, even when the database is up and [...]
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