Question

我有一个SQL字符串，我需要从主要的＆＃39; FROM＆＃39;中获取表名。值。我需要找到最后一个＆＃39; FROM＆＃39;可能会或可能不会有其他约束的事件。以下是字符串的几种显示方式：

$input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account WHERE title = 'president'";
$input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account LIMIT 1";
$input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account OFFSET 3";
$input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account ANYTHING_HERE_REALLY";
$input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account";

所有人的预期输出是：帐户

从搜索论坛到任何游戏，这是我要去的方向，但我知道它不正确。

preg_match('/.*FROM\s([^]]+)\sWHERE/', $input, $output);

Answer 1

首先，使用正则表达式来级联内容（级联）查询是不好的做法。但是我们走了......

简单地匹配FROM之后的非空格序列。

注意：由于.*的Kleene星的贪婪，它肯定会寻找最新的匹配。您的模式实际上旨在通过期望WHERE子句来过度指定问题。

preg_match('/.*FROM\s+(\S+)/', $input, $output);

示例（使用给定的示例和交互式php -a）：

$ php -a
php > $input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account WHERE title = 'president'";
php > preg_match('/.*FROM\s+(\S+)/', $input, $output);var_dump($output);
array(2) {
  [0]=>
  string(80) "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account"
  [1]=>
  string(7) "Account"
}
php > $input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account LIMIT 1";
php > preg_match('/.*FROM\s+(\S+)/', $input, $output);var_dump($output);
array(2) {
  [0]=>
  string(80) "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account"
  [1]=>
  string(7) "Account"
}
php > $input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account OFFSET 3";
php > preg_match('/.*FROM\s+(\S+)/', $input, $output);var_dump($output);
array(2) {
  [0]=>
  string(80) "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account"
  [1]=>
  string(7) "Account"
}
php > $input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account ANYTHING_HERE_REALLY";
php > preg_match('/.*FROM\s+(\S+)/', $input, $output);var_dump($output);
array(2) {
  [0]=>
  string(80) "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account"
  [1]=>
  string(7) "Account"
}
php > $input = "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account";
php > preg_match('/.*FROM\s+(\S+)/', $input, $output);var_dump($output);
array(2) {
  [0]=>
  string(80) "SELECT title, (SELECT name FROM Contact WHERE name = 'foo') as name FROM Account"
  [1]=>
  string(7) "Account"
}

Answer 2

这应该适合你：

preg_match_all('/FROM\s?(\S+)/', $input, $output);

$输出：

Array
(
    [0] => Array
        (
            [0] => FROM Contact
            [1] => FROM Account
        )

    [1] => Array
        (
            [0] => Contact
            [1] => Account
        )

)

使用正则表达式在字符串中最后一次出现

2 个答案: