Programming

Difference Between DBMS and RDBMS

2007-05-10T23:40:00.000+06:00

DBMS - Database Management System

A Database Management System (DBMS) is a computer program that can access data in a database.

The DBMS program enables you to extract, modify, or store information in a database.

Different DBMS programs provides different functions for querying data, reporting data, and modifying data.

RDBMS - Relational Database Management System

A Relational Database Management System (RDBMS) is a Database Management System (DBMS) where the database is organized and accessed according to the relationships between data.

RDBMS was invented by IBM in the early 1970's.

RDBMS is the basis for SQL, and for all modern database systems like Oracle, SQL Server, IBM DB2, Sybase, MySQL, and Microsoft Access.

What is COBOL ?

2007-04-25T07:43:00.000+06:00

COBOL is a high-level programming language first developed by the CODASYL Committee (Conference on Data Systems Languages) in 1960. Since then, responsibility for developing new COBOL standards has been assumed by the American National Standards Institute (ANSI).

Three ANSI standards for COBOL have been produced: in 1968, 1974 and 1985. A new COBOL standard introducing object-oriented programming to COBOL, is due within the next few years.

The word COBOL is an acronym that stands for COmmon Business Oriented Language. As the the expanded acronym indicates, COBOL is designed for developing business, typically file-oriented, applications. It is not designed for writing systems programs. For instance you would not develop an operating system or a compiler using COBOL.

Basic PHP Tutorial

2007-04-10T09:42:00.000+06:00

What?
Okay, so here's the general idea of what I'm going to do in this tutorial:
Teach you the basics of PHP.
Simple as that…nothing more, nothing less…well, maybe a little more…
------------------------------------------------------------------------------------------
Okay, let's get started!
If you have a server, then great! If not…well, get one! Ask a friend, look online, anything! If it has PHP installed on the server, then you're set!
Once you have a server and an FTP account to transfer the files, we can start by making our first PHP program! To make a program with PHP, there are a few things you need to understand first:

Every PHP program MUST start and end with , respectively. You will see examples of this later.
All expressions must end with a semicolon ( ; )
A PHP file (.php) with HTML scripts in it WILL be read as HTML, unless inside tags. (examples are explained further down)

So, now that you're confused with all of that, let me clear something up with an example script. First, open notepad, or anything that can save a .php, in need of a good one?

Quote

Check out a couple of my favorites:

Araneae
Notepad 2

Code:

( //<-- the "//" indicates a one-line comment, and only everything after and on the same line as the "//", will be counted as a comment. // Please note that the "echo "Hello World!"; //"echo" is a basic PHP function that displays data in the form of a string. If you notice, I added the ‘;' at the end, and I put my string (Hello World!), in quotes. This means that it will echo it as a string.
/* This is an example of a Multi Line comment. It will only stop with the break symbol -->*/
?>)

Okay, confused? Good. Go upload that file to the server (save it as test.php). Now, go you your server, and view the file. Notice how it displays "Hello World!"? Good, catching on? Nice!

Now, a little bit harder...

Code:(

= "This is a variable set as a string.";
$my_number = 0;
// Here, I set two variables. In PHP, a variable is defined with a $, then a string. IE: My two variables are called my_string, and my_number, because they each start with a $.

/* Now that the two variables are set, let's do something with them.
First, I'll make it easy and just display what they equal */
echo "$my_string = ".$my_string."
$my_number = ".$my_number;
/* Notice how I used a ‘.' To append separate strings and variables together, this makes the echo function display multiple strings
and variables, with one execution…IE: Instead of doing this:
echo "$my_string = ";
echo $my_string;
echo "
";
echo "$my_number = ";
echo $my_number;
I just put it all in one echo. */
?>)

That's the basic overview of variables…they're simple once you get the hang of them. Now, to perform a function, such as add(+), multiply(*), divide(/), and subtract(-), you simply do this:

Code:(

//Set Initial Number
$num = 10;
//Make a new variable, and perform +
$add = $num+5;
//Make a new variable, and perform -
$sub = $num-5;
//Make a new variable, and perform *
$multiply = $num*5;
//Make a new variable, and perform /
$divide = $num/5;
//Echo all my variables
echo "$num =".$num;
echo "
$sub =".$sub;
echo "
$multiply =".$multiply;
echo "
$divide =".$divide;
?>)

If you're noticing, it's a LOT like Flash (if you know flash). It's just a bit more work (because it's all through text, no drawing and such). You set your variables (with the $, to define a variable), add a ; at the end of a function, and display data. Simple.
Now, how about some if() statements? Let's make it easy:

Code:

(//set number variable
$num = 5;
//run if() statement
if ($num == 5){
//if the if() statement is true, echo string
echo "$num is = to 5.";
} else {
//else, echo another string
echo "$num does not = 5.";
}
?>)

Now, that example is pretty pointless, because I set $num to 5 to start, so it will echo "$num is = to 5.", however, if you change $num to anything else, it will echo "$num does not = 5.". Now, how about some user input? If you haven't noticed from above, I can put some HTML scripts in the echo function, and it will work (the
, made a line break) IE:

Code:

(echo "This is an example of an HTML line break:
Top
Bottom";
?>

So, we know we can run HTML scripts, let's make HTML interact with PHP…yes, that's it! Here we go:

Code:

= $_POST['name'];
if (!$name){
echo "Please enter a name: ";
?>)

(
} else {
echo "Hello ".$name.", welcome!";
}
?>)

About PHP

2007-04-10T09:38:00.000+06:00

PHP is a powerful server-side scripting language for creating dynamic and interactive websites.

PHP is the widely-used, free, and efficient alternative to competitors such as Microsoft's ASP. PHP is perfectly suited for Web development and can be embedded directly into the HTML code.

The PHP syntax is very similar to Perl and C. PHP is often used together with Apache (web server) on various operating systems. It also supports ISAPI and can be used with Microsoft's IIS on Windows.

A Word About the Java Platform

2007-04-06T12:28:00.000+06:00

The Java platform consists of the Java application programming interfaces (APIs) and the Java¹ virtual machine (JVM).

Java APIs are libraries of compiled code that you can use in your programs. They let you add ready-made and customizable functionality to save you programming time.

The simple program in this lesson uses a Java API to print a line of text to the console. The console printing capability is provided in the API ready for you to use; you supply the text to be printed.

Java programs are run (or interpreted) by another program called the Java VM. If you are familiar with Visual Basic or another interpreted language, this concept is probably familiar to you. Rather than running directly on the native operating system, the program is interpreted by the Java VM for the native operating system. This means that any computer system with the Java VM installed can run Java programs regardless of the computer system on which the applications were originally developed.

For example, a Java program developed on a Personal Computer (PC) with the Windows NT operating system should run equally well without modification on a Sun Ultra workstation with the Solaris operating system, and vice versa.

SQL WHERE Clause

2007-03-30T17:43:00.000+06:00

The WHERE Clause

To conditionally select data from a table, a WHERE clause can be added to the SELECT statement.

Syntax

SELECT column FROM table
WHERE column operator value

With the WHERE clause, the following operators can be used:

Operator	Description
=	Equal
<>	Not equal
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal
BETWEEN	Between an inclusive range
LIKE	Search for a pattern
IN	If you know the exact value you want to return for at least one of the columns

Note: In some versions of SQL the <> operator may be written as !=

Using the WHERE Clause

To select only the persons living in the city "Sandnes", we add a WHERE clause to the SELECT statement:

SELECT * FROM Persons
WHERE City='Sandnes'

"Persons" table

LastName	FirstName	Address	City	Year
Hansen	Ola	Timoteivn 10	Sandnes	1951
Svendson	Tove	Borgvn 23	Sandnes	1978
Svendson	Stale	Kaivn 18	Sandnes	1980
Pettersen	Kari	Storgt 20	Stavanger	1960

Result

LastName	FirstName	Address	City	Year
Hansen	Ola	Timoteivn 10	Sandnes	1951
Svendson	Tove	Borgvn 23	Sandnes	1978
Svendson	Stale	Kaivn 18	Sandnes	1980

Using Quotes

Note that we have used single quotes around the conditional values in the examples.

SQL uses single quotes around text values (most database systems will also accept double quotes). Numeric values should not be enclosed in quotes.

For text values:

This is correct:
SELECT * FROM Persons WHERE FirstName='Tove'

This is wrong:
SELECT * FROM Persons WHERE FirstName=Tove

For numeric values:

This is correct:
SELECT * FROM Persons WHERE Year>1965

This is wrong:
SELECT * FROM Persons WHERE Year>'1965'

The LIKE Condition

The LIKE condition is used to specify a search for a pattern in a column.

Syntax

SELECT column FROM table
WHERE column LIKE pattern

A "%" sign can be used to define wildcards (missing letters in the pattern) both before and after the pattern.

Using LIKE

The following SQL statement will return persons with first names that start with an 'O':

SELECT * FROM Persons
WHERE FirstName LIKE 'O%'

The following SQL statement will return persons with first names that end with an 'a':

SELECT * FROM Persons
WHERE FirstName LIKE '%a'

The following SQL statement will return persons with first names that contain the pattern 'la':

SELECT * FROM Persons
WHERE FirstName LIKE '%la%'

Select Statement (last part)

2007-03-22T09:21:00.000+06:00

Semicolon after SQL Statements?

Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server.

Some SQL tutorials end each SQL statement with a semicolon. Is this necessary? We are using MS Access and SQL Server 2000 and we do not have to put a semicolon after each SQL statement, but some database programs force you to use it.

The SELECT DISTINCT Statement

The DISTINCT keyword is used to return only distinct (different) values.

The SELECT statement returns information from table columns. But what if we only want to select distinct elements?

With SQL, all we need to do is to add a DISTINCT keyword to the SELECT statement:

Syntax

SELECT DISTINCT column_name(s)
FROM table_name

Using the DISTINCT keyword

To select ALL values from the column named "Company" we use a SELECT statement like this:

SELECT Company FROM Orders

"Orders" table

Company	OrderNumber
Sega	3412
W3Schools	2312
Trio	4678
W3Schools	6798

Result

Company
Sega
W3Schools
Trio
W3Schools

Note that "W3Schools" is listed twice in the result-set.

To select only DIFFERENT values from the column named "Company" we use a SELECT DISTINCT statement like this:

SELECT DISTINCT Company FROM Orders

Result:

Company
Sega
W3Schools
Trio

Now "W3Schools" is listed only once in the result-set.

SQL SELECT

2007-03-11T23:28:00.000+06:00

The SQL SELECT statement is used to select data from a SQL database table. This is usually the very first SQL command every SQL newbie learns and this is because the SELECT SQL statement is one of the most used SQL commands.

Please have a look at the general SQL SELECT syntax:

SELECT Column1, Column2, Column3,
FROM Table1

The list of column names after the SQL SELECT command determines which columns you want to be returned in your result set. If you want to select all columns from a database table, you can use the following SQL statement:

SELECT *
FROM Table1

When the list of columns following the SELECT SQL command is replaced with asterix (*) all table columns are returned. Word of caution here, it’s always better to explicitly specify the columns in the SELECT list, as this will improve your query performance significantly.

The table name following the SQL FROM keyword (in our case Table1) tells the SQL interpreter which table to use to retrieve the data.

Why Learn SQL ? First Steps of Database Programming

2007-03-09T19:52:00.000+06:00

SQL is a standard computer language for accessing and manipulating databases.

SQL is short for Structured Query Language and is a widely used database language, providing means of data manipulation (store, retrieve, update, delete) and database creation.

Almost all modern Relational Database Management Systems like MS SQL Server, Microsoft Access, MSDE, Oracle, DB2, Sybase, MySQL, Postgres and Informix use SQL as standard database language. Now a word of warning here, although all those RDBMS use SQL, they use different SQL dialects. For example MS SQL Server specific version of the SQL is called T-SQL, Oracle version of SQL is called PL/SQL, MS Access version of SQL is called JET SQL, etc.

My SQL tutorial will teach you how to use commonly used SQL commands and you will be able to apply most of the knowledge gathered from this SQL tutorial to any of the databases above.

What is SQL?

SQL stands for Structured Query Language
SQL allows you to access a database
SQL is an ANSI standard computer language
SQL can execute queries against a database
SQL can retrieve data from a database
SQL can insert new records in a database
SQL can delete records from a database
SQL can update records in a database
SQL is easy to learn

SQL is a Standard - BUT....

SQL is an ANSI (American National Standards Institute) standard computer language for accessing and manipulating database systems. SQL statements are used to retrieve and update data in a database. SQL works with database programs like MS Access, DB2, Informix, MS SQL Server, Oracle, Sybase, etc.

Unfortunately, there are many different versions of the SQL language, but to be in compliance with the ANSI standard, they must support the same major keywords in a similar manner (such as SELECT, UPDATE, DELETE, INSERT, WHERE, and others).

Note: Most of the SQL database programs also have their own proprietary extensions in addition to the SQL standard!

SQL Database Tables

A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.

Below is an example of a table called "Persons":

LastName	FirstName	Address	City
Hansen	Ola	Timoteivn 10	Sandnes
Svendson	Tove	Borgvn 23	Sandnes
Pettersen	Kari	Storgt 20	Stavanger

The table above contains three records (one for each person) and four columns (LastName, FirstName, Address, and City).

SQL Queries

With SQL, we can query a database and have a result set returned.

A query like this:

SELECT LastName FROM Persons

Gives a result set like this:

LastName
Hansen
Svendson
Pettersen

Note: Some database systems require a semicolon at the end of the SQL statement. We don't use the semicolon in our tutorials.

SQL Data Manipulation Language (DML)

SQL (Structured Query Language) is a syntax for executing queries. But the SQL language also includes a syntax to update, insert, and delete records.

These query and update commands together form the Data Manipulation Language (DML) part of SQL:

SELECT - extracts data from a database table
UPDATE - updates data in a database table
DELETE - deletes data from a database table
INSERT INTO - inserts new data into a database table

SQL Data Definition Language (DDL)

The Data Definition Language (DDL) part of SQL permits database tables to be created or deleted. We can also define indexes (keys), specify links between tables, and impose constraints between database tables.

The most important DDL statements in SQL are:

CREATE TABLE - creates a new database table
ALTER TABLE - alters (changes) a database table
DROP TABLE - deletes a database table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index

What Is JDBC?

2007-03-07T07:44:00.000+06:00

Working with leaders in the database field, JavaSoft developed a single API for database access--JDBC. As part of this process, they kept three main goals in mind:

JDBC should be an SQL-level API.

JDBC should capitalize on the experience of existing database APIs.

JDBC should be simple.

An SQL-level API means that JDBC allows us to construct SQL statements and embed them inside Java API calls. In short, you are basically using SQL. But JDBC lets you smoothly translate between the world of the database and the world of the Java application. Your results from the database, for instance, are returned as Java variables, and access problems get thrown as exceptions. Later on in the book, we go a step further and talk about how we can completely hide the existence of the database from a Java application using a database class library.

Because of the confusion caused by the proliferation of proprietary database access APIs, the idea of a universal database access API to solve this problem is not a new one. In fact, JavaSoft drew upon the successful aspects of one such API, Open DataBase Connectivity (ODBC). ODBC was developed to create a single standard for database access in the Windows environment. Although the industry has accepted ODBC as the primary means of talking to databases in Windows, it does not translate well into the Java world. First of all, ODBC is a C API that requires intermediate APIs for other languages. But even for C developers, ODBC has suffered from an overly complex design that has made its transition outside of the controlled Windows environment a failure. ODBC's complexity arises from the fact that complex, uncommon tasks are wrapped up in the API with its simpler and more common functionality. In other words, in order for you to understand a little of ODBC, you have to understand a lot.

In addition to ODBC, JDBC is heavily influenced by existing database programming APIs such as X/OPEN SQL Call Level Interface. JavaSoft wanted to re-use the key abstractions from these APIs, which would ease acceptance by database vendors and capitalize on the existing knowledge capital of ODBC and SQL CLI developers. In addition, JavaSoft also realized that deriving an API from existing ones can provide quick development of solutions for database engines that support the old protocols. Specifically, JavaSoft worked in parallel with Intersolv to create an ODBC bridge that maps JDBC calls to ODBC calls, thus giving Java applications access to any database management system (DBMS) that supports ODBC.

JDBC attempts to remain as simple as possible while providing developers with maximum flexibility. A key criterion employed by JavaSoft is simply asking whether database access applications read well. The simple and common tasks use simple interfaces, while more uncommon or bizarre tasks are enabled through extra interfaces. For example, three interfaces handle a vast majority of database access. JDBC nevertheless provides several other interfaces for handling more complex and unusual tasks.

What is Database ?

2007-03-01T16:39:00.000+06:00

A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.

In computing, databases are sometimes classified according to their organizational approach. The most prevalent approach is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object -oriented programming database is one that is congruent with the data defined in object classes and subclasses.

Computer databases typically contain aggregations of data records or files, such as sales transactions, product catalogs and inventories, and customer profiles. Typically, a database manager provides users the capabilities of controlling read/write access, specifying report generation, and analyzing usage. Databases and database managers are prevalent in large mainframe systems, but are also present in smaller distributed workshation and mid-range systems such as the AS/400 and on personal computers.SQL (Structured Query Language) is a standard language for making interactive queries from and updating a database such as IBM's DB2, Microsoft's Access, and database products from Oracle, Sybase, and Computer Associates.

Defination of Computer programming

2007-02-27T18:12:00.000+06:00

Computer programming (often shortened to programming or coding) is the process of writing, testing, and maintaining the source code of computer programs. The source code is written in a programming language. This code may be a modification of existing source or something completely new. The process of writing source code requires expertise in many different subjects, including knowledge of the application domain and algorithms to implement the desired behavior. Within software enginnering, programming (the implementation) is regarded as one phase in a software development process.

In some specialist applications or extreme situations a program may be written or modified (known as patching) by directly storing the numeric values of the machine code instructions to be executed into memory.

Sorry for few days

2007-02-25T08:08:00.000+06:00

Dear all, this site is under construction. Don't worry, just follow the links.. hrhelal.

Hello ! Hello !! Hello !!!

2007-02-25T07:58:00.000+06:00

Hello Everyone . Welcome to my new blog......