Mysql Drupal 7 db_选择嵌套选择查询

如何将嵌套的select查询转换为Drual 7 db_select？以下是问题查询：

select 
    * 
from 
    tbl_word 
where 
    EngWord like '%apple%' or 
    WordID in (
        select 
            WordID 
        from 
            tbl_subword 
        where 
            EngWord like '%apple%'
    );

---

从语义上讲，这很简单：

$term = 'apple';

$sub_query = db_select('tbl_subword')
  ->fields('tbl_subword', array('WordID'))
  ->condition('EngWord', '%' . db_like($term) . '%'), 'LIKE');

$query = db_select('tbl_word')
  ->fields('tbl_word')
  ->condition(db_or()
    ->condition('EngWord', '%' . db_like($term) . '%', 'LIKE')
    ->condition('WordID', $sub_query, 'IN')
  );

$results = $query->execute()->fetchAll();

---

看到了吗，这不会产生一个，在主查询中，我认为他需要，或者子查询的术语？太好了！它工作正常。只要在导致解析错误的条件下修复额外的braket。