PHP，AJAX，MySQL的复选框过滤，以及在and/OR之间切换

我正在尝试使用复选框来筛选搜索结果。在SELECT查询中，AND和OR都需要使用，具体取决于选中了多少个复选框和哪些复选框。这是HTML:

        <table>
            <tr>
                <th>Filter Results</th>
            </tr>
            <tr>
                <td>By chipset manufacturer:</td>
                <td><input name="by_amd" id="amdF" type="checkbox" value="1" />AMD</td>
                <td><input name="by_ati" id="atiF" type="checkbox" value="2" />ATI</td>
                <td><input name="by_nvid" id="nvidiaF" type="checkbox" value="3" />nVidia</td>
            </tr>
            <tr>
                <td>By year released:</td>
                <td><input name="by_2014" id="2014F" type="checkbox" value="2014" />2014</td>
                <td><input name="by_2013" id="2013F" type="checkbox" value="2013" />2013</td>
                <td><input name="by_2012" id="2012F" type="checkbox" value="2012" />2012</td>
                <td><input name="by_2011" id="2011F" type="checkbox" value="2011" />2011</td>
            </tr>
        </table>

和PHP：

// create base SELECT query
        $select = 'SELECT GPUProductName, GPUChip, GPUReleaseDate, GPUBus, GPUMemory, GPUClock, GPUMemClock, GPUAddStats'; 
        $from = ' FROM GPU'; 
        $where = ' WHERE TRUE'; 
        // create search filters
        $opts = isset($_POST['filterOpts']) ? $_POST['filterOpts'] : array('');
        // By chipset manufacturer
        if (in_array("by_amd", $opts)){
          $where .= " AND CMid = 1";
        }
        if (in_array("by_ati", $opts)){
          $where .= " AND CMid = 2";
        }
        if (in_array("by_nvid", $opts)){
          $where .= " AND CMid = 3";
        }
        // by release year
        if (in_array("by_2014", $opts)){
          $where .= " AND YEAR(GPUReleaseDate)='2014'";
        }
        // build complete SELECT query
        $query = $select . $from . $where;
        return $query;

如果选择"by ATI"answers"by AMD"，SELECT语句应分别为WHERE CMid = 2 OR CMid = 1。如果添加"到2014"，SELECT语句应为WHERE YEAR(GPUReleaseYear) = 2014 AND CMid = 2 OR CMid = 1。基本上，从同一类别（可以说）中挑选的过滤器应该用OR连接，从不同类别中挑选的滤波器应该用and连接。在PHP中，我如何根据从相同和/或不同类别中选中的复选框数量创建正确的SELECT语句？