Why I cant update rows with PDO using prepare function? - php

Question

I have an SQL $query like this;
UPDATE `tags` SET `tags.name` = :name,
`tags.slug` = :slug,
`tags.date_published` = :date_published,
`tags.meta_title` = :meta_title,
`tags.meta_description` = :meta_description,
`tags.meta_keywords` = :meta_keywords
WHERE `tags.id` = :id
And my $values array;
Array
(
[:name] => iphone
[:slug] => iphone
[:date_published] => 2016-03-27
[:meta_title] => iphone Yazıları
[:meta_description] => iphone hakkında son gelişmeler ve faydalı bilgiler.
[:meta_keywords] => iphone yazıları, iphone hakkında bilgiler, iphone haberleri
[:id] => 24
)
I'm trying to update one row with PDO's prepare function;
$sth = $this->db->prepare($query);
$sth->execute($values);
echo "affected rows: ".$sth->rowCount(); // prints 0
return $sth->rowCount() ? true : false;
And I get no errors but rows are not affected after execute the query. Where is my mistake?
mysql tags table
edit:
I'm creating values array like this;
$params = array(
"id", "name", "slug", "date_published",
"meta_title", "meta_description", "meta_keywords");
$values = array();
foreach ($params as $key) {
#$values[$key] = $_POST[$key];
}
And this is how I create the query;
$query = "UPDATE `$table` SET";
$values = array();
/* Add field names and placeholders to query. */
foreach ($params as $key => $value) {
$query .= " `{$table}.{$key}` = :" . $key . ",";
$values[":" . $key] = $value;
}
/* Remove last comma. */
$query = substr($query, 0, -1);
/* Build where condition. */
if ($cond) {
$query .= " WHERE ";
foreach ($cond as $key => $value) {
$query .= " `{$table}.{$key}` = :" . $key . ",";
$values[":" . $key] = $value;
}
/* Remove last comma. */
$query = substr($query, 0, -1);
}

Answer 1

You're escaping the column names incorrectly. For example, the back ticks should not enclose the whole of tags.name, but rather the table and column names separately:
`tags`.`name`
Checking the output of PDO::errorInfo() confirms this (emulated prepares must be set to false in order to see this, however).
General notes:
You don't need to specify the colon prefix for the keys of the array being bound (likewise when explicitly binding columns via bindParam() or bindValue()).
You should avoid using back ticks in your PDO queries. They're a MySQL-specific feature, and PDO is not a SQL abstraction layer (thereby preventing one of the major benefits of PDO - portability).