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PHP Programming

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 1995.

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PHP Programming

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  1. PHP Programming

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

  3. Background • Personal Home Page – C kind of scripts written in Perl language, by Rasmus Lerdorf in 1995. • He called the language as PHP/FI – Personal Home Page / Forms Interpreter. • 1997 Version 2.0 was released • Then came 3.0, 4.0. They were called PHP simply • Recent version is PHP 5.2.3

  4. 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

  5. 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 */

  6. Sample PHP <html> <body> <?php echo “hello”; ?> </html> The above program will display hello in the browser

  7. 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

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

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

  10. 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;

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

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

  13. Functions • Function returning value <?php function add($a,$b) { return ($a + $b); } ?> When called like <?php echo add(1,2);?> we will get an output 3 in the browser.

  14. 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

  15. 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

  16. 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

  17. 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);

  18. 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.

  19. 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

  20. 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.

  21. 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

  22. 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.

  23. 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);

  24. 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

  25. 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.

  26. 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.

  27. 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.

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