Get colon-prefixed placeholder names from a SQL string

I will make this quick and simple

I have a query and I want to split it so that it returns an array with words after the : symbol. This is what I have so far and it does as expected but returns the whole string before the matched needle. I just want the array to contain words after the : symbol.

$query = "SELECT user_name FROM test WHERE user_name = :user_name";
$arr = preg_split('/[:]/', $query, 0); 
print_r($arr);

This returns

Array
(
    [0] => SELECT user_name FROM test WHERE user_name = 
    [1] => user_name
)

Try this:

preg_match_all("/:(\w+)/", $string, $matches);

By doing this, all your elements that are after a : will be in $matches[1] sub-array. I'm assuming you want to handle SQL statements with multiple named parameters. So for example:

SELECT user_name FROM test WHERE user_name = :user_name and last_name = :last_name

Will result in $matches being:

array(2) {
  [0]=>
  array(2) {
    [0]=>
    string(10) ":user_name"
    [1]=>
    string(10) ":last_name"
  }
  [1]=>
  array(2) {
    [0]=>
    string(9) "user_name"
    [1]=>
    string(9) "last_name"
  }
}