如何將普通的SQL查詢轉換為Zend_Db_Select？

Question

嗨，我想將我的普通mysql查詢轉換為zend.db.select;

我要使用此腳本：

$select = $db->select();

// Add a FROM clause
$select->from( ...specify table and columns... )

// Add a WHERE clause
$select->where( ...specify search criteria... )

// Add an ORDER BY clause
$select->order( ...specify sorting criteria... );

$select->limit(20, 10);

對於我下面的查詢

SELECT 
    IF(derived_messages.toid = '$user', derived_messages.fromid, 
    derived_messages.toid) friend1,c.UserName,
    derived_messages.message, derived_messages.fromid, derived_messages.toid,
    derived_messages.is_read,derived_messages.type,derived_messages.id as mesid,                    
    derived_messages.date,
    (SELECT M.message_id FROM messagesmapped M where M.message_id= derived_messages.id AND M.user_id ='$user' AND M.important = 1) as MesMapid
    FROM 
    (               
    SELECT * 
    FROM messages
    WHERE messages.deleted_by NOT 
    IN ( $user ) 
    ORDER BY Date DESC      
    ) derived_messages
    INNER JOIN Users c ON c.MemberID = IF(derived_messages.toid = '$user', derived_messages.fromid, 
    derived_messages.toid)
    WHERE (derived_messages.id IN 
    (SELECT M.message_id FROM messagesmapped M where M.message_id= derived_messages.id AND M.user_id ='$user' AND M.important = 1)                  
    AND 
    (derived_messages.toid='$user' OR derived_messages.fromid='$user'))

    GROUP BY friend1 ASC 
    ORDER BY derived_messages.date DESC, derived_messages.id DESC LIMIT $limit $offset

我希望有人可以幫忙。

謝謝。

Answer 1

有可能但不太可能有人會為您編寫查詢。

我對處理此類查詢的建議是將每個子查詢編寫為自己的Zend_Db_Select對象，然后使用已經具有對象的子查詢來構建最終查詢。

Zend_Db_Select不直接支持IF函數，因此，您將需要使用Zend_Db_Expr將該語句添加到您的選擇中。

---

這是我正在談論的基本示例。 讓我們構建以下查詢：

SELECT IF(msg.toId = 'drew010', msg.fromId, msg.toId), id, name, age, history.ip
FROM users
JOIN history ON users.id = history.userId
WHERE users.id = (
    SELECT id FROM users WHERE loginCount > 1000
)
GROUP BY id,
ORDER BY age DESC

首先建立選擇用戶的子選擇，其中loginCount > 1000。

$subquery1 = $db->select()
                ->from('users', array('id'))
                ->where('loginCount > ?', 1000);

接下來，使用IF函數構建外部查詢：

$cols  = array(
    new Zend_Db_Expr('IF(' . $db->quoteInto('msg.toId = ?', 'drew010') . '), msg.fromId, msg.toId'),
    'id', 'name', 'age'
);

$query = $db->select()
            ->from('users', $cols)
            ->join('history', 'users.id = history.userId', array('ip'))
            ->where('id = ?', $subquery1)
            ->group('id')
            ->order('age DESC');

echo $query;

輸出：

SELECT
  IF(msg.toId = 'drew010', msg.fromId, msg.toId),
  `users`.`id`,
  `users`.`name`,
  `users`.`age`,
  `history`.`ip`
FROM `users`
INNER JOIN `history`
  ON users.id = history.userId
WHERE id = (
    (SELECT `users`.`id`
    FROM `users`
    WHERE (loginCount > 1000))
)
GROUP BY `id`
ORDER BY `age` DESC

---

因此，解決方法是先將整個查詢分解為單個查詢，然后構造外部查詢。 只要有耐心，慢慢來。 然后閱讀Zend_Db_Select文檔，以全面了解您所擁有的內容。