PHP AND MYSQL PHP and My SQL PHP

PHP AND MYSQL

PHP and My. SQL • PHP has functions that allow access to My. SQL Databases • Access is very easy – 1. Connect – 2. Select Database – 3. Query – 4. Close connection

1. Connect $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password');

2. Select Database $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); $db_selected = mysql_select_db('foo', $link);

3. Query $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); $db_selected = mysql_select_db('foo', $link); $result = mysql_query("DELETE FROM table; ", $link);

4. Close $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); $db_selected = mysql_select_db('foo', $link); $result = mysql_query("DELETE FROM table; ", $link); mysql_close($link);

mysql_query • INSERT, UPDATE, DELETE, DROP – Returns true or false • SELECT – Returns resource on success, false on error – The returned resource should be passed to mysql_fetch_array()

Retrieving Table $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); $db_selected = mysql_select_db('foo', $link); $result = mysql_query("SELECT * FROM table; ", $link); while ($row = mysql_fetch_array($result)) { print($row[0]); print($row[1]); } mysql_close($link);

Retrieving Table $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); $db_selected = mysql_select_db('foo', $link); $result = mysql_query("SELECT * FROM table; ", $link); while ($row = mysql_fetch_array($result)) { print($row["id"]); print($row["name"]); } mysql_close($link);

Error Handling • Every function in the previous code examples could fail – Connection can fail, sql query can fail etc. • Usually you exit the script when DB fails. • With exit($status) – function, you can stop the execution of the script.

Example of Error Handling 1 $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password'); if( ! $link ) { exit("Error connecting to database"); }

Example of Error Handling 2 $link = mysql_connect('mysql_server', 'mysql_user', 'mysql_password') or exit("Error connecting to database");