教义返回错误与"eq"，否与"in"

Question

使用Symfony和Doctrine，我在"eq"子查询中出现错误：

还好，没有错误：

public function getForums()
{
$qb = $this->createQueryBuilder('fc');
return $qb
->innerJoin('fc.versions', 'fcv')
->innerJoin('fc.versions', 'fcvl', 'WITH', $qb->expr()->in(
'fcvl.id',
$this->_em->createQueryBuilder()
->select('MAX(v.id)')
->from(ForumCategoryVersion::class, 'v')
->where('v.forumCategory = fc')
->getDQL()
))
->select('fc, fcv')
->getQuery()
->getResult();
}

用eq替换in：

public function getForums()
{
$qb = $this->createQueryBuilder('fc');
return $qb
->innerJoin('fc.versions', 'fcv')
->innerJoin('fc.versions', 'fcvl', 'WITH', $qb->expr()->eq(
'fcvl.id',
$this->_em->createQueryBuilder()
->select('MAX(v.id)')
->from(ForumCategoryVersion::class, 'v')
->where('v.forumCategory = fc')
->getDQL()
))
->select('fc, fcv')
->getQuery()
->getResult();
}

我有这个错误：

〔语法错误〕第0行，第208列：错误：需要Literal，得到了SELECT

Answer 1

您需要使用括号((用于子查询：

->innerJoin('fc.versions', 'fcvl', 'WITH', $qb->expr()->eq(
'fcvl.id',
'(' . $this->_em->createQueryBuilder()
->select('MAX(v.id)')
->from(ForumCategoryVersion::class, 'v')
->where('v.forumCategory = fc')
->getDQL() . ')'
))

参考

• Mysql equal子查询
• 用教义做一件事