php mysqli WHERE IN (?,?,? ...)

Question

According to http://us2.php.net/manual/en/mysqli-stmt.bind-param.php, the different types are:

i   corresponding variable has type integer
d   corresponding variable has type double
s   corresponding variable has type string
b   corresponding variable is a blob and will be sent in packets

However, how can you handle this:

->prepare("SELECT blabla FROM foo WHERE id IN (?)")

Where ? would be a list of ids. There could be one or more items:

$ids = "3,4,78";
->bind_param('s',$ids);

Is that possible?

I'd like to use prepared statements because it will be executed in a loop.

Answer 1

The proper syntax would be

->prepare("SELECT blabla FROM foo WHERE id IN (?, ?, ?)")

for 3 items in that array, for example. You would then have to bind each of those items individually using bind_param().

If you don't have a size guarantee on the array, you'll have to write a couple helper functions to generate your SQL with the proper number of "?"'s and bind statements.

Answer 2

I think I found the answer to my question:

->prepare("SELECT stuff FROM table_name WHERE id IN (?)");

$itemList = implode(',',$items);
$children->bind_param('s',$itemList);

Seems to be working fine when using a string with coma-separated values. I'm still checking if the results are really accurate ...

Answer 3

If you have a list of variables that differs in size every call that you wanto to bind to an IN-statement, the most simple way would be to generate the SQL string programatically and use a loop to bind the variables:

/**
 * @param  array  $values
 * @param  mysqli $db
 * @return mysqli_stmt
 */
function bindInValues(array $values, mysqli $db)
{
    $sql = sprintf('SELECT blabla FROM foo WHERE id IN (%s)',
        implode(', ', array_fill(0, count($values), '?'))
    );
    $stmt = $db->prepare($sql);
    foreach ($values as $value) {
        $stmt->bind_param('s', $value);
    }
    return $stmt;
}

If you like call_user_func_array you can use dynamic method invocation and go along without a loop.

/**
 * @param  array  $values
 * @param  mysqli $db
 * @return mysqli_stmt
 */
function bindInValues(array $values, mysqli $db)
{
    $sql = sprintf('SELECT blabla FROM foo WHERE id IN (%s)',
        implode(', ', array_fill(0, count($values), '?'))
    );
    $stmt = $db->prepare($sql);
    array_unshift($values, implode('', array_fill(0, count($values), 's')));
    call_user_func_array(array($stmt, 'bind_param'), $values);
    return $stmt;
}