帮助 sql 查询中逗号的正则表达式

Question

我有一个类似的 SQL 查询：

select column1 as a, DECODE(x, 1, x1, 2, x2) as column2, 
    DECODE(y, 1, y1, 2, y2) as column3 from test

我想选择以下逗号（用**,**表示）：

select a as column1 **,** DECODE(x, 1, x1, 2, x2) as column2 **,** 
    DECODE(y, 1, y1, 2, y2) as column3 from test

我为此使用/(?!(.*\))),|,(?=.*\()/gs，但你怎么能在http://gskinner.com/RegExr/ 中看到第一个DECODE 中的逗号也被选中了。我需要该正则表达式来解析此代码中使用的选择中的列：

$select = substr($sql, 6, strpos($sql, "from") - 6);
$parts = preg_split('/(?!(.*\))),|,(?=.*\()/s', $select);

$columns = array();
foreach($parts as $p) {
    @list($id, $alias) = preg_split('/( as )/', $p);
    $columns[trim($id)] = trim($alias);
}

Answer 1

试试这个：

<?php

$sql = "select a as column1, DECODE(x, 1, x1, 2, x2) as column2, DECODE(y, 1, y1, 2, y2) as column3 from test";

$select = substr($sql, 6, strpos($sql, "from") - 6);
$select .=',';
$parts = preg_split('/ as (.*?),/s', $select, NULL, PREG_SPLIT_DELIM_CAPTURE);
$columns = array();
for($i=0; $i<count($parts)-1; $i+=2) {
  $columns[trim($parts[$i])] = $parts[$i+1];
}
print_r($columns);

?>

更新：

对于更复杂的查询，您应该使用 SQL 解析器。