Call to undefined method PDO::fetch()

Question

I know there are few other questions on here with this title, but they seem to be case specific or I just can't wrap my head around it but I'm getting that error on this code, and I can't figure out why.

$db = new PDO($dsn, $username, $password);
$query = "Select * FROM book INNER JOIN course
          ON book.course = course.courseID
          ORDER BY courseTitle";

//query result
$books = array();
$sth = $db->query($query);
while( $row = $db->fetch(PDO::FETCH_ASSOC) ) {
    $books[] = $row; // appends each row to the array
}

I thought maybe my query was wrong, so I tried an example from a PDO tutorial, and I got the same type of error. Is there something I have to declare or am I leaving something out?

I changed to $sth, now I get "Call to a member function fetch() on a non-object" error — john, May 01 '13 at 05:52
[PDO query fails but I can't see any errors. How to get an error message from PDO?](http://stackoverflow.com/questions/15990857/reference-frequently-asked-questions-about-pdo#15990858) — DCoder, May 01 '13 at 05:54
Then `query` returned `false` because your query was bad. Use `var_dump($db->errorInfo())` to figure out what's wrong. — deceze, May 01 '13 at 05:54
my query is incorrect, I will work on the syntax. thank you. — john, May 01 '13 at 05:58

bestprogrammerintheworld · Accepted Answer · 2013-05-01T06:01:10.017

12

You should use $sth instead of $db when using PDO-functions relevant to query on the resultset from the query.

$db = new PDO($dsn, $username, $password);
$query = "Select * FROM book INNER JOIN course
ON book.course = course.courseID
ORDER BY courseTitle";

//query result
$books = array();
$sth = $db->query($query);
while( $row = $sth->fetch(PDO::FETCH_ASSOC) ) {
  $books[] = $row; // appends each row to the array
}

When debugging PDO. Add this line after creation of PDO-object:

$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

Then exceptions will be thrown when there are errors in the query/queries.

edited May 01 '13 at 06:01

answered May 01 '13 at 05:48

bestprogrammerintheworld

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Well, `$db` is *also* a PDO object on which you can use "PDO functions"... – deceze May 01 '13 at 05:51
hey best, thank you for responding, I made the change you supplied, and now I get this error. 'Call to a member function fetch() on a non-object' is book not a member object? – john May 01 '13 at 05:52
@deceze - ah I know, I explained it rather poorely. Maybe it's more clear now? – bestprogrammerintheworld May 01 '13 at 05:53
@john - my guess is that you've never used PDO before on the computer you're developing? Is PDO active? Check it with phpinfo(). – bestprogrammerintheworld May 01 '13 at 05:54
2

@bestprogrammerintheworld: if PDO weren't active, it would crash on `new PDO(...)`. I'm betting on a syntax error in the query itself. – DCoder May 01 '13 at 05:55
@DCoder, yes of course. That's so true! :-) – bestprogrammerintheworld May 01 '13 at 05:56
It is a syntax error in the query, thank you. – john May 01 '13 at 05:59
@john - ok, good that you figured out the problem! :-) – bestprogrammerintheworld May 01 '13 at 06:03

Call to undefined method PDO::fetch()

1 Answers1