convert from mysql php script to pdo - php

Question

I am actually new to PDO
Here I am trying to fetch data from mysql and show in xml.
I have done it using mysql, but I could not be able to done it using PDO.
Here is my PHP code
<?php
error_reporting(E_ALL);
$host = "localhost";
$user = "root";
$pass = "root";
$database = "my_db";
// replace by a real *.xsl file, e.g.
// $xslt_file = "exam.xsl";
$xslt_file = FALSE;
// If true, will output XML without XSLT
$raw = TRUE;
$SQL_query = "SELECT * FROM `battery` order by waste asc";
$DB_link = mysql_connect($host, $user, $pass) or die("Could not connect to host.");
mysql_select_db($database, $DB_link) or die ("Could not find or access the database.");
$result = mysql_query ($SQL_query, $DB_link) or die ("Data not found. Your SQL query didn't work... ");
$left = "<";
$right = ">";
if ($xslt_file or $raw) {
// we produce XML
header("Content-type: text/xml");
$XML = "<?xml version=\"1.0\"?>\n";
if (!$raw) $XML .= "<?xml-stylesheet href=\"$xslt_file\" type=\"text/xsl\" ?>";
}
else {
// we produce HTML. All XML tags are replaced by printable entities
$XML = "Don't forget to create an XSLT file .... <p>";
$XML .= "<pre>\n";
$left = "<";
$right = ">";
}
// root node
$XML .= $left . "result" . $right . "\n";
// rows
while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
$XML .= "\t" . $left. "row" . $right . "\n"; // creates either "<row>" or "<row>"
$i = 0;
// cells
foreach ($row as $cell) {
// Escaping illegal characters
$cell = str_replace("&", "&", $cell);
$cell = str_replace("<", "<", $cell);
$cell = str_replace(">", ">", $cell);
$cell = str_replace("\"", """, $cell);
$col_name = mysql_field_name($result,$i);
// creates the "<tag>contents</tag>" representing the column, either as XML or for display in HTML
$XML .= "\t\t" . $left . $col_name . $right . $cell . $left . "/" . $col_name . $right ."\n";
$i++;
}
$XML .= "\t" . $left. "/row" . $right . "\n";
}
$XML .= $left . "/result" . $right . "\n";
echo $XML;
if (!$xslt_file && !$raw) echo "</pre>";
?>
I am trying a lot, but i could not be able to done it using PDO
Please i need some help.
Any Help will be appreciated.
My PDO code that i tried is
<?php
$dbtype = "mysql";
$dbhost = "localhost";
$dbname = "my_db";
$dbuser = "root";
$dbpass = "root";
$conn = new PDO("mysql:host=$dbhost;dbname=$dbname",$dbuser,$dbpass);
$xslt_file = FALSE;
$raw = TRUE;
$SQL_query = "SELECT * FROM `battery` order by waste asc";
$result = $conn->query($SQL_query);
$left = "<";
$right = ">";
if ($xslt_file or $raw) {
header("Content-type: text/xml");
$XML = "<?xml version=\"1.0\"?>\n";
if (!$raw) $XML .= "<?xml-stylesheet href=\"$xslt_file\" type=\"text/xsl\" ?>";
}
else {
$XML = "Don't forget to create an XSLT file .... <p>";
$XML .= "<pre>\n";
$left = "<";
$right = ">";
}
$XML .= $left . "result" . $right . "\n";
while($row = $result->fetch(PDO::FETCH_ASSOC)) {
$XML .= "\t" . $left. "row" . $right . "\n"; // creates either "<row>" or "<row>"
$i = 0;
// cells
foreach ($row as $cell) {
// Escaping illegal characters
$cell = str_replace("&", "&", $cell);
$cell = str_replace("<", "<", $cell);
$cell = str_replace(">", ">", $cell);
$cell = str_replace("\"", """, $cell);
$col_name = $result->fetchAll(PDO::FETCH_COLUMN);
// creates the "<tag>contents</tag>" representing the column, either as XML or for display in HTML
$XML .= "\t\t" . $left . $col_name . $right . $cell . $left . "/" . $col_name . $right ."\n";
$i++;
}
$XML .= "\t" . $left. "/row" . $right . "\n";
}
$XML .= $left . "/result" . $right . "\n";
echo $XML;
if (!$xslt_file && !$raw) echo "</pre>";
?>
But it shows nothing

Answer 1

The correct way to fetch column names is
$q = $dbh->prepare("DESCRIBE tablename");
$q->execute();
$table_fields = $q->fetchAll(PDO::FETCH_COLUMN);
however as you are fetching an assoc you could just change your foreach loop to this:
foreach ($row as $col_name => $cell) {
There may be other issues, have you tried using print_r on the result of each PDO function call to check at what point it is failing?

Answer 2

you connect to the database like this :
$dbhost = "localhost";
$dbname = "testcreate";
$dbuser = "root";
$dbpass = "mysql";
try {
$db = new PDO('mysql:host='.$dbhost.';dbname='.$dbname.';charset=utf-8', ''.$dbuser.'', ''.$dbpass.'');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
echo 'Error : <br>' . $e->getMessage();
}
PS: You dont need the try and the catch, but we used to get the error and handle it in a nice way as we want to
and next we query like this :
$db->query(SELECT * FROM node WHERE node_name='$nodename'");
and we fetch it like this :
$query = $db->query(SELECT * FROM node WHERE node_name='$nodename'");
$row = $query->fetch(PDO::FETCH_OBJ);
and now you use $row->name for example
here is more about PDO::FETCH
PDO::FETCH_ASSOC: returns an array indexed by column name as returned in your result set
PDO::FETCH_BOTH (default): returns an array indexed by both column name and 0-indexed column number as returned in your result set
PDO::FETCH_BOUND: returns TRUE and assigns the values of the columns in your result set to the PHP variables to which they were
bound with the PDOStatement::bindColumn() method
PDO::FETCH_CLASS: returns a new instance of the requested class, mapping the columns of the result set to named properties in the
class. If fetch_style includes PDO::FETCH_CLASSTYPE (e.g.
PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE) then the name of the class
is determined from a value of the first column.
PDO::FETCH_INTO: updates an existing instance of the requested class, mapping the columns of the result set to named properties in
the class
PDO::FETCH_LAZY: combines PDO::FETCH_BOTH and PDO::FETCH_OBJ, creating the object variable names as they are accessed
PDO::FETCH_NUM: returns an array indexed by column number as returned in your result set, starting at column 0
PDO::FETCH_OBJ: returns an anonymous object with property names that correspond to the column names returned in your result set