submitting arrays of values to queries using PDO - php

Question

I notice that these two ways of structuring a query with PHP PDO, both return the same data.
//prepare with $dbh->prepare
$w_ft = "36";
$sth = $dbh->prepare("SELECT * FROM main_products_common_dimensions WHERE w_ft = :w_ft");
$sth->bindParam(':w_ft', $theId, PDO::PARAM_INT);
$sth->execute();
$result = $sth->fetchAll(); //PHP array of data
//prepare with pg_prepare()
$result = pg_prepare($con, "my_query", 'SELECT * FROM main_products_common_dimensions WHERE w_ft = $1');
$result = pg_execute($con, "my_query", array("48")); //A query result resource on success or FALSE on failure.
while ($row = pg_fetch_assoc($result)){
echo $row['w_ft'] . "<BR>";
}
I read at http://php.net/manual/en/function.pg-execute.php that the second way returns "A query result resource on success or FALSE on failure." So I tried to iterate through it with pg_fetch_assoc(). It works, but is that not deprecated along with the rest of the pg_sql functions? Should I be using something in the PDO to look at the results of the query?
For this reason, I'm inclined to use the first method while using PDO. Is this the norm?
My question is how to submit multiple values to either method. Neither method works when I try to submit an array to the prepared statement
$w_ft = array("48", "36");
$result = pg_execute($con, "my_query", array("48", "36"));
I thought that I was able to submit multiple values to the query in this way. How can I do this?
Thank you

Answer 1

Looks like you're taking execute array wrong.
It takes values not for the consequent executions but for one execution only.
So, number of values should be equal to number of placeholders.
So it goes
$sql = 'SELECT * FROM table WHERE w_ft = $1 OR w_ft = $2 OR w_ft = $3'
for your array("48", "36", "12")
I am not a PG user though, so, I can confuse some syntax.

Answer 2

PDO is an agnostic database access API for PHP. This means, whatever your database is, you will be able to use the same objects and methods to query it and fetch results. PDO was the first step toward database abstraction layers in PHP.
The pg_* API is, afaik, not going to be deprecated and is dedicated to Postgres. It also contains functions that were not implemented in PDO (like binary escaping or event notifier functions amongst others).
The choice between PDO and dedicated library is often hidden by the choice of the Model Manager you use in your controllers code. Either it can be Object Relational Mapper over an abstraction layer like ORMs (Doctrine, Propel and many others) or it can be an Object Model Manager (OMM) dedicated to Postgresql like Pomm.
In both ways, you do not need to prepare statements, manage the columns types nor results cursors (btw, using PDO::fetch_all() will dump all results in memory), the database layer handles that for you. Your above query would be written like:
// Using Pomm
// SELECT * FROM main_products_common_dimensions WHERE w_ft = ?
// Returns a MainProductsCommonDimensions instance
$object = $connection
->getMapFor('\Database\Schema\MainProductsCommonDimensions')
->findWhere('w_ft = ?', array(48))
->current(); // fetch only the first result.
Note that both ORMs and OMMs do propose handy query builder:
$where = \Pomm\Query\Where::createWhere('w_ft = ?', array(48))
->orWhere('w_ft = ?', array(12))
->orWhere('w_ft = ?', array(66));
// which is pretty much the same as
$where = \Pomm\Query\Where::createIn('w_ft', array(48, 12, 66));
// SELECT * FROM main_products_common_dimensions WHERE w_ft IN (?, ?, ?);
$collection = $connection
->getMapFor('\Database\Schema\MainProductsCommonDimensions')
->findWhere($where); // Return an Iterable cursor over results
// display 48, 12 and 66 fetching one result at the time in memory:
foreach($collection as $object)
{
printf("W_FT = '%d'.\n", $object['w_ft']);
}
Using those layers above PDO offers numerous advantages, the main one is to focus more on what you want instead of dealing with weird APIs (yes PDO is weird as almost any lib in PHP). Furthermore, since PDO is just an access layer it will return results as arrays of strings (binary or not). Boolean in Postgres are 't' and 'f' and thus will need to be converted to PHP proper Boolean (sic) type to be used. ORMs and OMMs do propose such translation mechanisms and Pomm as being dedicated to Postgres also support Arrays, HStore, LTree, geometric and composite types conversions and more.