Whats wrong with my PDO mysql query [duplicate] - php

Question

This question already has an answer here:
Invalid Parameter Number. Parameter not defined
(1 answer)
Closed 8 years ago.
Here is my code
$sql3= "select *
from comments
where status=:status
limit=:limit
offset=:offset
order by time desc";
$query3= $pdo->prepare($sql3);
$query3->bindValue(":status",'n');
$query3->bindValue(":limit",$per_page);
$query3->bindValue(":offest",$offset);
$query3->execute();
$comments=$query3->fetchall();
Here comments is my table name status and time is two column in my table . Whenever I run this code , It shows a warning
Warning: PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: parameter was not defined in E:\XAMPP\htdocs\parlament\user\logged_in_area.php
What does this mean ?

Answer 1

The answer depends of what are limit and offset.
If they're columns names...
You can't use these reserved keywords for column names without backticks
You need to add a AND / OR operator between your lines
$sql3= "select *
from comments
where status=:status
and `limit`=:limit
and `offset`=:offset
order by time desc";
$query3= $pdo->prepare($sql3);
$query3->bindValue(":status", 'n');
$query3->bindValue(":limit", $per_page);
$query3->bindValue(":offest", $offset);
$query3->execute();
$comments=$query3->fetchall();
If they're keywords...
The syntax is LIMIT <n>, not LIMIT = <n> (same for OFFSET)
It better to specify their type with PDO::PARAM_INT (same for OFFSET)
ORDER BY must be added before LIMIT and OFFSET
$sql3= "select *
from comments
where status=:status
order by time desc
limit :limit
offset :offset";
$query3= $pdo->prepare($sql3);
$query3->bindValue(":status", 'n');
$query3->bindValue(":limit", (int)$per_page, PDO::PARAM_INT);
$query3->bindValue(":offset", (int)$offset, PDO::PARAM_INT);
$query3->execute();
$comments=$query3->fetchall();

Answer 2

Adding my answer because nobody has mentioned this specific part yet...
MySQL is very picky about the data type of LIMIT parameters. You pretty much need to use bindParam(':limit', $per_page, PDO::PARAM_INT). I assume the same for OFFSET.
So, in summary
// because E_WARNING level errors are insufficient
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$stmt = $pdo->prepare('SELECT * FROM `comments` WHERE `status` = :status ORDER BY `time` DESC LIMIT :limit OFFSET :offset');
$stmt->bindValue(':status', 'n');
$stmt->bindParam(':limit', $per_page, PDO::PARAM_INT);
$stmt->bindParam(':offset', $offset, PDO::PARAM_INT); // spelt "offset"
$stmt->execute();
$comments = $stmt->fetchAll(PDO::FETCH_ASSOC);

Answer 3

Try this->
$sql3= "select *
from comments
where status = ?
limit ?
offset ?
order by time desc";
$query3= $pdo->prepare($sql3);
$query3->execute(array('n',$per_page,$offset));
$comments=$query3->fetchall();

Answer 4

Not sure about that but I think that PDO::bindValue / bindParam works with variable references. You cannot set a static value as parameter.
Try to replace
$query3->bindValue(":status",'n');
by
$n_value = 'n';
$query3->bindValue(":status",$n_value);
You also forgot the "AND" Keyword between your conditions

Answer 5

You're missing the AND or OR keyword in statement. Also, LIMIT is a reserved keyword, you'll need to backtick it or rename it to something else if you don't want to do that.

Answer 6

$sql3= "select *
from comments
where status = ?
limit= ?
offset= ?
order by time desc";
$query3= $pdo->prepare($sql3);
$query3->bindValue(1,'n');
$query3->bindValue(2,$per_page);
$query3->bindValue(3,$offset);
$query3->execute();
$comments=$query3->fetchall();