PHP Programming

Topics Background and History of PHP Installation Comments in PHP Variables Conditions Loops Functions File Handling Database Handling (MySQL, MSSQL, ODBC)

Background Personal Home Page – C kind of scripts written in Perl language, by Rasmus Lerdorf in He called the language as PHP/FI – Personal Home Page / Forms Interpreter Version 2.0 was released Then came 3.0, 4.0. They were called PHP simply Recent version is PHP 5.2.3

Installation Apache server need to be installed first The config file for apache server will be present in the conf folder under the apache installed directory Set the DocumentRoot to the path where the PHP files will be stored Install PHP. Point apache conf directory when it asks so and select the appropriate web server. Move the PHP.ini file to C:\WNDOWS directory

PHP Comments All php files are saved with extension.php The can be written in notepad or any text editor Single line comment –// this is single line comment Multi line comment –/*…. This is a multi line comment */

Sample PHP The above program will display hello in the browser

Variables Variables start with a $ symbol Variables can contain _ or numbers or alphabets $ should be followed by _ or alphabet and not by a number PHP is loosely typed language. There is no strict data typing Variable can be assigned with any values

Conditions If else if(condn) {….} elseif(condn) {….} else { ….} Switch case switch(var) { case c1: statements;break. Default: statements; break; }

Loops For for(intialisation;condition;increment/decrement) { statements } While while(condn) { ….} Do While do {….} while(condn);

Functions and Parameters PHP functions need to be defined with key word function It can have zero or more values (parameters) Functions may or may not return values If a function need to return value, the last statement of the function should be return –return value;

Functions Parameter less function <?php function sayHi() { echo “hi”; } ?> This can be called as in the program

Functions Parameterized function <?php function greet($name) { echo “Hello “. $name; } ?> This can be called This gives an output Hello Ram

Functions Function returning value <?php function add($a,$b) { return ($a + $b); } ?> When called like we will get an output 3 in the browser.

File Handling This involves 5 tasks –Opening a file –Reading data from a file –Displaying the read data –Writing contents to another file –Closing a file

Opening a file $fp = fopen(‘filename’,’mode’); Eg $fp = fopen(‘c:\abc.txt’,’r’); –This opens a file abc.txt in read only mode Available modes: –r – read only –w – write only –w+ - read write –A – append – adding to the end

Reading a file Several methods are available –fread(filepointer,no of bytes to read) –fgetc(filepointer) – Reads character by character –fgets(filepointer) – Reads line by line The read content can be stored in a variable $data = fread($fp,10) – this reads 10 characters from file pointed by file pointer $fp and stores in $data If we want to read characters till end, we need to use a loop with condition checking for End of File

Writing to file We can use echo $data, to print the contents read from the file to browser Or we can open another file in write mode and put the contents to that file using either of these methods –fwrite(filepoiner,data); –fputc(filepointer,char); - writes character by character –fputs(filepointer,line); - writes line by line Eg - fwrite($fpw,$data);

Closing a file feof(fp) – Checks for end of file. Returns –1 if EOF is reached. Otherwise returns 0 To close a file use fclose(filepointer) method Eg. fclose($fp); –This closes the file pointed by $fp.

Database Handling PHP can connect to –MySQL –MSSQL –Access and other databases like oracle, postgre sql etc There are separate methods available for connecting to the databases

MySQL and MSSQL Connection mysql_connect(dbserver,userid,password) mssql_connect(dbserver,userid,password) –These methods are used for connecting to MySQL and MSSQL server using a userid and password $con = mysql_connect(‘localhost’,’root’,’root’); –This gets a connection to the local mysql server using the credentials root and root –If server cannot be connected, it will throw an error stating the problem Note: Mysql and MSSQL can be accessed in identical way except for the preceeding mysql or mssql. So will use mysql henceforth.

MySQL Select DB mysql_select_db(connection,dbname) mysql_select_db($con,”test”); –This will select the db test under the server localhost –If unable to select the database, an error will be thrown

MySQL Execute Query mysql_query(connection,sql statement); This will execute the sql statement on the database and store the result in a variable Eg –$rs = mysql_query($con,select stmt); –The rows of select statement will be stored in $rs –$row = mysql_fetch_array($rs); This will fetch a row and store in $row Values can be accessed like - $row[“ID”] – returns value of column ID in the fetched row.

MySQL and MSSQL Close To close a db connection we have close method –mysql_close(connection); –mssql_close(connection); Example –mysql_close($con); –mssql_close($con);

ODBC Data handling Connect to a data source –odbc_connect(dsn,uname,pwd); –DSN – Data Source Name –Go to Control Panel -> Administrative Tools -> Datasources (ODBC) –Click on ODBC and select System DSN tab. –Click Add and choose Access Database (mdb) and click Finish –In the dialog that appears, give DSN Name and Description

ODBC Data handling Contd.. –Click on Select under Database section –Choose a mdb (access database file) and give OK $conn=odbc_connect('nwind','',''); –Here nwind is the DSN that we have created in our system to access a database –We have not given any user name or password during DSN creation –So those fields are left empty.

Selecting rows from a table $rs = odbc_exec($conn,$sql); –$conn – connection string –$sql – SQL query to select rows from table –$rs is the result set of the query execution odbc_fetch_row($rs) –This command fetches row by row from the result set $cid = odbc_result($rs,"CustomerID"); –This command fetches value for the column CustomerID from the current row and stores it in the variable $cid.

Closing Connection odbc_close(connection) –This function closes the connection obtained and releases the same to the connection pool odbc_close($conn); –The connection defined by $conn is released and no query can be executed using this connection variable hence forth.