從數據庫中選擇偏移量

Question

 <?php
      switch ($page)
        {
        case 1:

            $query = $this->db->get_where('ao', array('banned' => '0'), 28, 0);
            break;
        case 2:
            $query = $this->db->get_where('ao', array('banned' => '0'), 56, 29);
            break;
        case 3:
            $query = $this->db->get_where('ao', array('banned' => '0'), 84, 57);
            break;
        case 4:
            $query = $this->db->get_where('ao', array('banned' => '0'), 112, 85);
            break;
        case 5:
            $query = $this->db->get_where('ao', array('banned' => '0'), 140, 113);
            break;
        case 6:
            $query = $this->db->get_where('ao', array('banned' => '0'), 168, 141);
            break;
        case 7:
            $query = $this->db->get_where('ao', array('banned' => '0'), 196, 169);
             break;
        case 8:
            $query = $this->db->get_where('ao', array('banned' => '0'), 224, 197);
             break;
        case 9:
            $query = $this->db->get_where('ao', array('banned' => '0'), 252, 225);
             break;
        case 10:
            $query = $this->db->get_where('ao', array('banned' => '0'), 280, 253);
            break;
        case 11:
            $query = $this->db->get_where('ao', array('banned' => '0'), 308, 281);
            break;
        case 12:
            $query = $this->db->get_where('ao', array('banned' => '0'), 336, 309);
            break;
        case 13:
            $query = $this->db->get_where('ao', array('banned' => '0'), 364, 337);
            break;
        case 14:
            $query = $this->db->get_where('ao', array('banned' => '0'), 392, 365);
            break;
        case 15:
            $query = $this->db->get_where('ao', array('banned' => '0'), 420, 393);
            break;                  
        default:
            $query = $this->db->get_where('ao', array('banned' => '0'), 28, 0);

}

？>

這就是我目前正在做的事情。是否有更好的方法來做到這一點？ 每個案例都是一個頁面，我從page / $ num調用它

我如何從上面試圖實現的同一件事中獲得28條最新條目？

---

羅伯特·皮特的最新消息

• $page = 2; //page 2
• $limit = 30; //per page
• $offset = ($page - 1 * $offset); //30

然后您像這樣查詢數據庫：

SELECT * FROM table LIMIT $offset,$limit

Answer 1

您只能對無限頁面使用兩個查詢：

<?php
    switch($page) {
       case 1:
          $query = $this->db->get_where('ao', array('banned' => '0'), 28, 0);
          break;
       default:
          $query = $this->db->get_where('ao', array('banned' => '0'), 28 * (int)$page, 28 * (int)$page - 27);
          break;
    }
?>

（可選）您可以將頁面大小存儲在變量中並使用該變量，而不是對其進行硬編碼：

<?php
    $ps = 28; // page size
    switch($page) {
       case 1:
          $query = $this->db->get_where('ao', array('banned' => '0'), $ps, 0);
          break;
       default:
          $query = $this->db->get_where('ao', array('banned' => '0'), $ps * (int)$page, $ps * (int)$page - ($ps - 1));
          break;
    }
?>

這樣，您可以通過更改一個變量來更改頁面大小，而不是在所有代碼中進行查找/替換。

Answer 2

也許這會有所幫助：

$sqltorun="SET @rownum = 0;
SET @startRow = ".$StartRow."; # your $page
SET @maxRows = ".$MaxRows."; # limit. how much rows per page
SELECT * FROM (SELECT @rownum:=@rownum+1 as rownum, t.* FROM (SELECT @rownum:=0) r, YOURTABLE t where banned=>0 order by SOMETHING OR DONT ORDERBY) t WHERE rownum BETWEEN @startRow and @startRow + @maxRows and rownum!=@startRow";