如何更正preg_match_all正則表達式中子模式的結果？

Question

我有這樣的代碼：

$query = 'CREATE table "msg" ("myid" INT(10) UNSIGNED , "user" INT(10) UNSIGNED , "new_mes" SMALLINT(5) UNSIGNED , "total_mes" MEDIUMINT(8) UNSIGNED , "lastdate" DATETIME , PRIMARY KEY ("ids"), KEY ("lastdate"))'; 

我試圖讓主鍵和鍵使用此subpaterns：

preg_match_all('/(?:\WPRIMARY\W*KEY\W?\()(?P<PRIMARY_KEY>[^)]+)|'. 
     '(?:\W*KEY\W?\()(?P<KEY>[^)]+)/i',$query,$results); 
     $primary_key = isset($results['PRIMARY_KEY'][0]) ? $results['PRIMARY_KEY'][0] : ''; 
     $key = isset($results['KEY'][0]) ? $results['KEY'][0] : ''; 
    print_r($results); 

我得到這樣的輸出：

Array 
(
    [0] => Array 
     (
      [0] => PRIMARY KEY ("ids" 
      [1] =>),KEY ("lastdate" 
     ) 

    [PRIMARY_KEY] => Array 
     (
      [0] => "ids" 
      [1] => 
     ) 

    [1] => Array 
     (
      [0] => "ids" 
      [1] => 
     ) 

    [KEY] => Array 
     (
      [0] => 
      [1] => "lastdate" 
     ) 

    [2] => Array 
     (
      [0] => 
      [1] => "lastdate" 
     ) 
) 

我找的用雙引號括起來的單詞。結果幾乎可以找到，但我更願意在第一個索引[0]中獲取兩個單詞「ids」和「lastdate」。你能解釋爲什麼它發生在第一個索引中的第一個詞被放置，而第二個索引被放置在第二個索引中？爲什麼在第二和第一個索引中有空字符串。

有沒有辦法如何讓兩個詞在索引0？只是爲了簡化代碼。

Answer 1

你可以檢查你的正則表達式如何與Regex101一起工作，在右上角。

的另一種方法來完成這項工作（see online demo）：

<?php 
// I added a primary key `myid` to demonstrate a capture with several keywords 
$query = 'CREATE table "msg" ("myid" INT(10) UNSIGNED , "user" INT(10) UNSIGNED , "new_mes" SMALLINT(5) UNSIGNED , "total_mes" MEDIUMINT(8) UNSIGNED , "lastdate" DATETIME , PRIMARY KEY ("ids", "myid"), KEY ("lastdate"))'; 

// 1. Note the \b anchor to ensure that the capture begins at the start of a word 
// 2. PREG_SET_ORDER to keep structure simplier 
preg_match_all('#\b((?:PRIMARY\s*?)?KEY) \(([^\)]*)\)#i', $query, $results, PREG_SET_ORDER); 

$primary_keys = []; 
$keys = []; 

foreach ($results as $result) { 
    $values = explode(',', $result[2]); // get separate words 
    array_walk($values, function (&$v) { $v = trim($v, ' "'); }); // remove quotes and spaces 
    if (0 === stripos($result[1], 'PRIMARY')) { 
     $primary_keys = array_merge($primary_keys, $values); 
    } 
    else { 
     $keys = array_merge($keys, $values); 
    } 
} 

echo "Found primary keys:\n"; 
print_r($primary_keys); 
echo "Found keys:\n"; 
print_r($keys); 

echo "\n\$results:\n"; 
print_r($results); 

結果：

Found primary keys: 
Array 
(
    [0] => ids 
    [1] => myid 
) 
Found keys: 
Array 
(
    [0] => lastdate 
) 

$results: 
Array 
(
    [0] => Array 
     (
      [0] => PRIMARY KEY ("ids", "myid") 
      [1] => PRIMARY KEY 
      [2] => "ids", "myid" 
     ) 

    [1] => Array 
     (
      [0] => KEY ("lastdate") 
      [1] => KEY 
      [2] => "lastdate" 
     ) 

) 

您可以在Regex101看到this new version是更高效，the old one 377個步驟VS 904獲取結果的步驟。