How does one output data using mySQL PDO? - php

Question

New to mySQL PDO. I have read other answers here and read tutorials and am finally taking the plunge. Problem is I cannot seem to output data. Hence, can someone assess my code to ensure it is correct? Also, is the system I am using to query the db efficient and clean and secure? thanks
$pdo --- the correct connection information is in this line but has been removed ---
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// SELECT sql query
try {
$thedate='2013-06-03';
$rotation=1;
$stmt = $pdo->prepare("SELECT * FROM sched_main_2013 WHERE thedate=:thedate AND rotation=:rotation");
$stmt->bindValue(':thedate', $thedate, PDO::PARAM_STR);
$stmt->bindValue(':rotation', $rotation, PDO::PARAM_INT);
$stmt->execute();
$stmt->setFetchMode(PDO::FETCH_ASSOC);
}
catch(PDOException $ex) {
echo $ex->getMessage();
}
while($rows = $stmt->fetch()) {
echo $rows['thedate'] . "\n";
echo $rows[assignedRad] . "\n";
echo $rows[rotation] . "\n";
}
// close the connection
$pdo = null;
This code outputs nothing. No errors. Nothing at all.
By the way, the table exists and the SELECT * FROM works fine when I manually run the mySQL statement, so data does exist with this query.

Answer 1

Try
while($rows = $stmt->fetch()) {
echo $rows['thedate'] . "\n";
echo $rows[assignedRad] . "\n";
echo $rows[rotation] . "\n";
}
To
while($rows = $stmt->fetch()) {
echo $rows['thedate'] . "\n";
echo $rows['assignedRad'] . "\n";
echo $rows['rotation'] . "\n";
}
Debug 01
Maybe you can try this to test whether you truly receive any data from database
print_r($stmt->fetchAll());
Instead of your while-loop
Debug 02
Try the simple query that you strongly believe there will be no SQL error for example:
SELECT * FROM sched_main_2013
Without any value binding.
Debug 03
Try another query with WHERE condition, but no binding
SELECT * FROM sched_main_2013 WHERE thedate='2013-06-03' AND rotation=1

Answer 2

You told that var_dump($row) gives you FALSE. The documentation says:
The return value of this function on success depends on the fetch type. In all cases, >FALSE is returned on failure.
Add the following line:
while($row = $stmt->fetch()) {
echo $row['thedate'] . "\n";
echo $row['assignedRad'] . "\n";
echo $row['rotation'] . "\n";
}
if($row === FALSE) {
var_dump($stmt->errorInfo());
die();
}
Further note: You originally named the return value of $stmt->fetch() $rows (plural) instead of $row. I'm not sure whether you know that the method will return a single row each time it is called.

Answer 3

What it have to be
$sql = "SELECT * FROM sched_main_2013 WHERE thedate=? AND rotation=?";
$data = array('2013-06-03', 1);
$stmt = $pdo->prepare($sql);
$stmt->execute($data);
$rows = $stmt->fetchAll();
var_dump($rows);
$sql = "SELECT * FROM sched_main_2013";
$data = array();
$stmt = $pdo->prepare($sql);
$stmt->execute(array());
$rows = $stmt->fetchAll();
var_dump($rows);
If second query returns the rows while first doesn't - there is no data found.
If both returns no rows - then it is caused by bad database design which is clearly seen from the table name, which should never have a postfix like this