Passing an array to a query using a WHERE clause

问题

Given an array of ids $galleries = array(1,2,5) I want to have a SQL query that uses the values of the array in its WHERE clause like:

SELECT *
FROM galleries
WHERE id = /* values of array $galleries... eg. (1 || 2 || 5) */

How can I generate this query string to use with MySQL?

回答1:

BEWARE! This answer contains a severe SQL injection vulnerability. Do NOT use the code samples as presented here, without making sure that any external input is sanitized.

$ids = join("','",$galleries);   
$sql = "SELECT * FROM galleries WHERE id IN ('$ids')";

回答2:

Using PDO:^[1]

$in = join(',', array_fill(0, count($ids), '?'));
$select = <<<SQL
    SELECT *
    FROM galleries
    WHERE id IN ($in);
SQL;
$statement = $pdo->prepare($select);
$statement->execute($ids);

Using MySQLi ^[2]

$in = join(',', array_fill(0, count($ids), '?'));
$select = <<<SQL
    SELECT *
    FROM galleries
    WHERE id IN ($in);
SQL;
$statement = $mysqli->prepare($select);
$statement->bind_param(str_repeat('i', count($ids)), ...$ids);
$statement->execute();
$result = $statement->get_result();

Explanation:

Use the SQL `IN()` operator to check if a value exists in a given list.

In general it looks like this:

expr IN (value,...)

We can build an expression to place inside the () from our array. Note that there must be at least one value inside the parenthesis or MySQL will return an error; this equates to making sure that our input array has at least one value. To help prevent against SQL injection attacks, first generate a ? for each input item to create a parameterized query. Here I assume that the array containing your ids is called $ids:

$in = join(',', array_fill(0, count($ids), '?'));

$select = <<<SQL
    SELECT *
    FROM galleries
    WHERE id IN ($in);
SQL;

Given an input array of three items $select will look like:

SELECT *
FROM galleries
WHERE id IN (?, ?, ?)

Again note that there is a ? for each item in the input array. Then we'll use PDO or MySQLi to prepare and execute the query as noted above.

Using the `IN()` operator with strings

It is easy to change between strings and integers because of the bound parameters. For PDO there is no change required; for MySQLi change str_repeat('i', to str_repeat('s', if you need to check strings.

^{^[1]: I've omitted some error checking for brevity. You need to check for the usual errors for each database method (or set your DB driver to throw exceptions).}

^{^[2]: Requires PHP 5.6 or higher. Again I've omitted some error checking for brevity.}

回答3:

ints:

$query = "SELECT * FROM `$table` WHERE `$column` IN(".implode(',',$array).")";

strings:

$query = "SELECT * FROM `$table` WHERE `$column` IN('".implode("','",$array)."')";

回答4:

Assuming you properly sanitize your inputs beforehand...

$matches = implode(',', $galleries);

Then just adjust your query:

SELECT *
FROM galleries
WHERE id IN ( $matches )

Quote values appropriately depending on your dataset.

回答5:

Use:

select id from galleries where id in (1, 2, 5);

A simple for each loop will work.

Flavius/AvatarKava's way is better, but make sure that none of the array values contain commas.

回答6:

As Flavius Stef's answer, you can use intval() to make sure all id are int values:

$ids = join(',', array_map('intval', $galleries));  
$sql = "SELECT * FROM galleries WHERE id IN ($ids)";

回答7:

For MySQLi with an escape function:

$ids = array_map(function($a) use($mysqli) { 
    return is_string($a) ? "'".$mysqli->real_escape_string($a)."'" : $a;
  }, $ids);
$ids = join(',', $ids);  
$result = $mysqli->query("SELECT * FROM galleries WHERE id IN ($ids)");

For PDO with prepared statement:

$qmarks = implode(',', array_fill(0, count($ids), '?'));
$sth = $dbh->prepare("SELECT * FROM galleries WHERE id IN ($qmarks)");
$sth->execute($ids);

回答8:

We should take care of SQL injection vulnerabilities and an empty condition. I am going to handle both as below.

For a pure numeric array, use the appropriate type conversion viz intval or floatval or doubleval over each element. For string types mysqli_real_escape_string() which may also be applied to numeric values if you wish. MySQL allows numbers as well as date variants as string.

To appropriately escape the values before passing to the query, create a function similar to:

function escape($string)
{
    // Assuming $db is a link identifier returned by mysqli_connect() or mysqli_init()
    return mysqli_real_escape_string($db, $string);
}

Such a function would most likely be already available to you in your application, or maybe you've already created one.

Sanitize the string array like:

$values = array_map('escape', $gallaries);

A numeric array can be sanitized using intval or floatval or doubleval instead as suitable:

$values = array_map('intval', $gallaries);

Then finally build the query condition

$where  = count($values) ? "`id` = '" . implode("' OR `id` = '", $values) . "'" : 0;

$where  = count($values) ? "`id` IN ('" . implode("', '", $values) . "')" : 0;

Since the array can also be empty sometimes, like $galleries = array(); we should therefore note that IN () does not allow for an empty list. One can also use OR instead, but the problem remains. So the above check, count($values), is to ensure the same.

And add it to the final query:

$query  = 'SELECT * FROM `galleries` WHERE ' . $where;

TIP: If you want to show all records (no filtering) in case of an empty array instead of hiding all rows, simply replace 0 with 1 in the ternary's false part.

回答9:

Safer.

$galleries = array(1,2,5);
array_walk($galleries , 'intval');
$ids = implode(',', $galleries);
$sql = "SELECT * FROM galleries WHERE id IN ($ids)";

回答10:

We can use this "WHERE id IN" clause if we filter the input array properly. Something like this:

$galleries = array();

foreach ($_REQUEST['gallery_id'] as $key => $val) {
    $galleries[$key] = filter_var($val, FILTER_SANITIZE_NUMBER_INT);
}

Like the example below:

$galleryIds = implode(',', $galleries);

I.e. now you should safely use $query = "SELECT * FROM galleries WHERE id IN ({$galleryIds})";

回答11:

Col. Shrapnel's SafeMySQL library for PHP provides type-hinted placeholders in its parametrised queries, and includes a couple of convenient placeholders for working with arrays. The ?a placeholder expands out an array to a comma-separated list of escaped strings*.

For example:

$someArray = [1, 2, 5];
$galleries = $db->getAll("SELECT * FROM galleries WHERE id IN (?a)", $someArray);

* Note that since MySQL performs automatic type coercion, it doesn't matter that SafeMySQL will convert the ids above to strings - you'll still get the correct result.

回答12:

You may have table texts (T_ID (int), T_TEXT (text)) and table test (id (int), var (varchar(255)))

In insert into test values (1, '1,2,3') ; the following will output rows from table texts where T_ID IN (1,2,3):

SELECT * FROM `texts` WHERE (SELECT FIND_IN_SET( T_ID, ( SELECT var FROM test WHERE id =1 ) ) AS tm) >0

This way you can manage a simple n2m database relation without an extra table and using only SQL without the need to use PHP or some other programming language.

回答13:

More an example:

$galleryIds = [1, '2', 'Vitruvian Man'];
$ids = array_filter($galleryIds, function($n){return (is_numeric($n));});
$ids = implode(', ', $ids);

$sql = "SELECT * FROM galleries WHERE id IN ({$ids})";
// output: 'SELECT * FROM galleries WHERE id IN (1, 2)'

$statement = $pdo->prepare($sql);
$statement->execute();

回答14:

Because the original question relates to an array of numbers and I am using an array of strings I couldn't make the given examples work.

I found that each string needed to be encapsulated in single quotes to work with the IN() function.

Here is my solution

foreach($status as $status_a) {
        $status_sql[] = '\''.$status_a.'\'';
    }
    $status = implode(',',$status_sql);

$sql = mysql_query("SELECT * FROM table WHERE id IN ($status)");

As you can see the first function wraps each array variable in single quotes (\') and then implodes the array.

NOTE: $status does not have single quotes in the SQL statement.

There is probably a nicer way to add the quotes but this works.

回答15:

Besides using the IN query, you have two options to do so as in an IN query there is a risk of an SQL injection vulnerability. You can use looping to get the exact data you want or you can use the query with OR case

1. SELECT *
      FROM galleries WHERE id=1 or id=2 or id=5;


2. $ids = array(1, 2, 5);
   foreach ($ids as $id) {
      $data[] = SELECT *
                    FROM galleries WHERE id= $id;
   }

回答16:

Below is the method I have used, using PDO with named placeholders for other data. To overcome SQL injection I am filtering the array to accept only the values that are integers and rejecting all others.

$owner_id = 123;
$galleries = array(1,2,5,'abc');

$good_galleries = array_filter($chapter_arr, 'is_numeric');

$sql = "SELECT * FROM galleries WHERE owner=:OWNER_ID AND id IN ($good_galleries)";
$stmt = $dbh->prepare($sql);
$stmt->execute(array(
    "OWNER_ID" => $owner_id,
));

$data = $stmt->fetchAll(PDO::FETCH_ASSOC);

回答17:

Safe way without PDO:

$ids = array_filter(array_unique(array_map('intval', (array)$ids)));

if ($ids) {
    $query = 'SELECT * FROM `galleries` WHERE `id` IN ('.implode(',', $ids).');';
}

(array)$ids Cast $ids variable to array
array_map Transform all array values into integers
array_unique Remove repeated values
array_filter Remove zero values
implode Join all values to IN selection

回答18:

Basic methods to prevent SQL injection are:

Use prepared statements and parameterized queries
Escaping the special characters in your unsafe variable

Using prepared statements and parameterized queries query is considered the better practice, but if you choose the escaping characters method then you can try my example below.

You can generate the queries by using array_map to add a single quote to each of elements in the $galleries:

$galleries = array(1,2,5);

$galleries_str = implode(', ',
                     array_map(function(&$item){
                                   return "'" .mysql_real_escape_string($item) . "'";
                               }, $galleries));

$sql = "SELECT * FROM gallery WHERE id IN (" . $galleries_str . ");";

The generated $sql var will be:

SELECT * FROM gallery WHERE id IN ('1', '2', '5');

Note: mysql_real_escape_string, as described in its documentation here, was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

mysqli_real_escape_string()

PDO::quote()

来源：https://stackoverflow.com/questions/907806/passing-an-array-to-a-query-using-a-where-clause

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