如何从preg_match_all正则表达式中的子模式中更正结果？

John Boe 发表于 Dev

约翰·波

我有以下代码：

$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") )';

我正在尝试使用以下子模式获取“主键”和“键”：

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);

我得到以下输出：

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"
        )
)

我寻找了用双引号引起来的单词。结果几乎可以找到，但我希望在第一个索引[0]中获得两个单词“ ids”和“ lastdate”。您能解释一下为什么将第一个单词放在第一个索引中而将第二个单词放在第二个索引中是为什么吗？以及为什么第二个和第一个索引上有空字符串。

有没有办法如何使两个单词都在索引0上？只是为了简化代码。

您可以在右上方的边栏中检查您的正则表达式如何与Regex101一起使用。

完成这项工作的另一种方法（请参见在线演示）：

<?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);

结果：

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"
        )

)