Zend框架2：SQL子查询

Question

在ZF1它的工作是这样的：

$selectColumns = array(
    '*', 
    'orders_total' => "(".$db->select()->from("orders", array("COUNT(*)"))->where("orders.parent_id=mytable.id").")", 
); 
$select = $db->select()->from('mytable', $selectColumns); 

如何在ZF2做到这一点？谢谢。

Answer 1

请试试这个。

$sql = new Sql($this->_adapter); 
$mainSelect = $sql->select()->from('mytable'); 
$subQry = $sql->select() 
     ->from('orders') 
     ->columns(array('orderCount' => new \Zend\Db\Sql\Expression('COUNT(orders.id)'))); 
$mainSelect->columns(
     array(
      'id', 
      'orders_total' => new \Zend\Db\Sql\Expression('?', array($subQry)), 
     ) 
); 

$statement = $sql->prepareStatementForSqlObject($mainSelect); 
$comments = $statement->execute(); 
$resultSet = new ResultSet(); 
$resultSet->initialize($comments); 

return $resultSet->toArray(); 

链接：ZF2 - subqueries

Answer 2

没有任何更多的信息，你可以尝试：

$selectColumns = array(
    '*', 
    'orders_total' => "(".$db->select()->from("orders", array("COUNT(*)"))->where("orders.parent_id", "mytable.id").")", 
); 
$select = $db->select()->from('mytable', $selectColumns); 

你需要在顶部使用语句添加：

use Zend\Db\Sql\Select; 
use Zend\Db\Sql\Where; 

Answer 3

你可以试试这个：

// Make your query here using the builder if you wish, 
// but we will need to convert to string for the Expression 
$sub = new Select('orders'); 
$sub->columns(array(new Expression('COUNT(*) as total'))) 
    ->where(array('id' => 4)) 
; 
// You could just create an expression.. 
$subquery = new \Zend\Db\Sql\Expression("({$sub->getSqlString()})"); 

$select = new \Zend\Db\Sql\select('tablename'); // this is inside a 

$select->columns(array('*', 'orders_total' => $subquery)); 

输出将如下所示：

SELECT 
    .*, 
    (SELECT COUNT(*) as total FROM "orders" WHERE "id" = '4') AS orders_total 
FROM tablename 

我还没有想出一个使用查询生成器执行这些查询而不必使用原始查询的好方法。

Answer 4

您可以尝试重组你的SQL语句是这样的：

SELECT 
    *, 
    SUM(IF(O.parent_id IS NULL, 0, 1)) AS orders_total 
FROM mytable 
    LEFT JOIN orders O ON mytable.id = O.parent_id 

，你可以代表使用Zend Framework 2为：

$select = new Select('mytable'); 
$select->columns(array(
    '*', 
    'orders_total' => new Expression("SUM(IF(O.parent_id IS NULL, 0, 1))") 
)); 
$select->join(array('O', 'orders'), 
       "mytable.id = O.parent_id", 
       Select::JOIN_LEFT); 
$select->group(array('mytable.id')); 

$result = $dbh->selectWith($select); 

假设$ dbh是您的数据库适配器。