How to create a string that contains the keys of a given array in PHP?

Question

I have an array holding this data:

Array ( 
  [1402377] => 7 
  [1562441] => 7 
  [1639491] => 9 
  [1256074] => 10 
 )

How can create a string that contains the keys of the above array? Essentially, I need to create a comma separated string that consists of an array's keys

The string would look like: 'key','key','key'

Do I need to create a new array consisting of the keys from an existing array?

The reason I need to do this is because I will be querying a MySQL database using a WHERE in () statement. I would rather not have to query the database using a foreach statement. Am I approaching this problem correctly?

I've tried using a while statement, and I'm able to print the array keys that I need, but I need those keys to be an array in order to send to my model.

The code that allowed me to print the array keys looks like this:

while($element = current($array)) {
            $x = key($array)."\n";
            echo $x;
            next($array);
        }

Be careful about [injection](http://unixwiz.net/techtips/sql-injection.html) vulnerabilities. Familiarize yourself with the [array functions](http://it.php.net/manual/en/ref.array.php). — outis, Jan 13 '12 at 07:28
possible duplicate of [PHP Splitting an Array into two arrays - keys array and values array](http://stackoverflow.com/questions/6234696/), [MySQL Prepared statements with a variable size variable list](http://stackoverflow.com/questions/327274/). — outis, Jan 13 '12 at 08:01
...[There is a way to get all keys of the array?](http://stackoverflow.com/questions/3407967/), [Print the keys of an array](http://stackoverflow.com/questions/3507381/), [Parameterizing an SQL IN clause?](http://stackoverflow.com/questions/337704/), [PreparedStatement IN clause alternatives?](http://stackoverflow.com/questions/178479/preparedstatement-in-clause-alternatives) — outis, Jan 13 '12 at 08:17

score 3 · Accepted Answer · answered Jan 13 '12 at 07:24

$string = implode(',', array_keys($array));

By the way, for looping over an array consider not using current and next but use foreach:

foreach ($array as $key => $value) {
    //do something
}

This will automatically iterate over the array until all records have been visited (or not at all if there are no records.

score 2 · Answer 2 · answered Jan 13 '12 at 07:24

2

$keys = array_keys($array);
$string = implode(' ',$keys);

In your case, were you are using the result in a IN clause you should do: $string = implode(',', $keys);

answered Jan 13 '12 at 07:24

Cyclonecode

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score 1 · Answer 3 · answered Jan 13 '12 at 07:24

1


$yourString = '';
foreach($yourArr as $key => $val) {
 $yourString .=$key.",";
}
echo rtrim($yourString, ",");

//OR
$yourString = implode(",", array_keys($yourArray));

See : array_keys

answered Jan 13 '12 at 07:24

Sudhir Bastakoti

99,167
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score 1 · Answer 4 · answered Jan 13 '12 at 07:27

1

implode(', ', array_keys($array));

answered Jan 13 '12 at 07:27

WoLfulus

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score 0 · Answer 5 · answered Jan 13 '12 at 07:25

0

Use php array_keys and implode methods

print implode(PHP_EOL, array_keys($element))

answered Jan 13 '12 at 07:25

Nazariy

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score 0 · Answer 6 · answered Jan 13 '12 at 07:31

0

The string would look like: 'key','key','key'

$string = '\'' . implode('\',\'', array_keys($array)) . '\'';

answered Jan 13 '12 at 07:31

OptimusCrime

14,662
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score 0 · Answer 7 · answered Jan 13 '12 at 08:15

Imploding the arguments and interpolating the result into the query can cause an injection vulnerability. Instead, create a prepared statement by repeating a string of parameter placeholders.

$paramList = '(' . str_repeat('?, ', count($array) - 1) . '?)'
$args = array_keys($array);
$statement = 'SELECT ... WHERE column IN ' . $paramList;
$query = $db->prepare($statement);
$query->execute($args);

How to create a string that contains the keys of a given array in PHP?

7 Answers7