Start coding in PHP

Start coding in PHP

Following tradition, we will begin coding with a “hello world” example. Fire up your text editor and type the following code for Start coding in PHP:

<HTML>  <?php  echo "Hello World";  ?>  </HTML>

Save the file as first.php and view it in the browser (remember to set the permission to chmod 775 first). The page shows “Hello World”. View the HTML source of this page through your browser. You will only see the text Hello World. This happened because PHP processed the code, and the code told PHP to output the string “Hello World”. Notice the . These are delimiters and enclose a block of PHP code. tells PHP to stop processing. All lines beyond this scope are passed as HTML to the browser.

Your first database to Start coding in PHP

Now that you have PHP running properly and have created your first script, let’s create a database and see what we can do with it. Drop to console and type in the following command:

mysqladmin -uroot create learndb

This creates a database named “learndb” for us to use. Here we have assumed that you are root user. If you are logged in as another user, just use the command mysqladmin -uusername -pyourpassword create learndb, replacing username and yourpassword with your username and password, respectively. If you are hosting your site through a hosting company, you probably don’t have permission to run mysqladmin. In this case, you have to ask your server administrator to create the database for you. Next we will create tables in this database and enter some information. Go to the console. Type:

You should see something like for Start coding in PHP:

Welcome to MySQL monitor. Commands end with ; or \g.  Your MySQL connection id is 5 to server version 3.22.34  Type 'help' for help.

Type this to  Start coding in PHP:

CONNECT learndb  CREATE TABLE personnel  (  id int NOT NULL AUTO_INCREMENT,  firstname varchar(25),  lastname varchar(20),  nick varchar(12),  email varchar(35),  salary int,  PRIMARY KEY (id),  UNIQUE id (id)  );  INSERT INTO personnel VALUES ('1','John','Lever','John', '[email protected]','75000');  INSERT INTO personnel VALUES ('2','Camilla','Anderson','Rose', '[email protected]','66000');  This creates a table with 5 fields and puts some information in it, as shown in Bellow

Now that we have a database with some information with it to Start coding in PHP, let’s see if we can view it with PHP. Save the following text as viewdb.php:

<HTML>  <?php  $db = mysql_connect("localhost", "root", "");  mysql_select_db("learndb",$db);  $result = mysql_query("SELECT * FROM personnel",$db);  echo "<TABLE>";  echo"<TR><TD><B>Full Name</B><TD><B>Nick Name</B><TD><B>Salary</B></TR>";  while ($myrow = mysql_fetch_array($result))  {  echo "<TR><TD>";  echo $myrow["firstname"];  echo " ";  echo $myrow["lastname"];  echo "<TD>";  echo $myrow["nick"];  echo "<TD>";  echo $myrow["salary"];  }  echo "</TABLE>";  ?>  </HTML>

Run it through your browser and you will see a personnel database. But what is this code doing and how is it generated? Let’s examine the code. First we declare a variable $db. In PHP we declare a variable by putting the ‘$’ sign before it. The string after $ is the name of that variable. We assign value to it byStart coding in PHP:

$variable_name=somevalue; (example: $count=4;)

Remember to put ‘;’ after all the lines that are executable in PHP. So we declare the variable $db and create a connection to the mysql database with the statement “mysql_connect(“localhost”, “root”, “”)”. In plain English, it means connect to MySQL database in localhost server with the username root and password “”. Replace them with your own username and password if they are different for Start coding in PHP. Then we assign a pointer to this database to $db; in other words, $db points to our database server localhost. Next we select the database with which we want to interact with the lines “mysql_select_db(“learndb”,$db);” which means we wish to use the database “learndb” located by the pointer variable $db. But we want information from the database, so we query the database with the lines “$result = mysql_query(“SELECT * FROM personnel”,$db);” The part “SELECT * FROM personnel” is an SQL statement (in case you don’t know SQL), which means select all the stuff from the database personnel, as shown in  for Start coding in PHP.

Start coding in PHP

Start coding in PHP

We run this query with the PHP command mysql_query() and save the result returned by the database to the variable $result. Now we can access the different data in the different rows of the database from the $result variable. We use the function mysql_fetch_array() to extract each row from $result and assign them to variable $myrow. So $myrow contains information about each row as opposed to all the rows in $result.Then we output the data contained in each row. “echo $myrow[“firstname”];” means send to output the value contained in the field “firstname” of the row contained in $myrow; in other words, we access different fields of the row with $myrow[“fieldname”]. We have used the while() loop here, which means as long as or while there are data to be extracted from $result, execute the lines within those brackets {}. Thus we get nicely formatted output in our browser. Viewing the PHP code and the HTML source from the browser side-by-side may help you easily understand the procedure. Congratulations! You have created your first dynamic page here for Start coding in PHP.