Php SQL中的条件聚合，在何时使用多个条件

我试图获取特定时间范围内的打印页数（今天打印、本周打印、今年打印、本月打印），并执行以下SQL查询：

$select2 = "SELECT 
                IF( station_name =  '',  'Unknown', station_name ) station_name, 
                station_name as db_name,    
                sum(case when year(print_date) = $year then print_pages end) as yearpages, 
                sum(case when (month(print_date) = $month and year(print_date) = $year) then print_pages end) as monthpages, 
                sum(case when (day(print_date) = $day and year(print_date) = $year and month(print_date) = $month) then print_pages end) as daypages, 
                sum(case when (week(print_date) = $week AND year(print_date) = $year AND month(print_date) = $month) then print_pages end) as weekpages
            FROM `file_prints`
            GROUP BY station_name;";

但是，当我在Zend PHP framework中执行查询后输出的数组中的一个元素上执行var转储时，我发现yearpages和monthpages是定义良好的（返回的值不是NULL），但是weekpages和daypages都是NULL，如下所示：

$rows = $_userTable->getAdapter()->fetchAll($select2);
        var_dump($rows[46]);
        print_r(array_keys($rows[46]));



array(6) { 
    ["station_name"]=> string(15) "uchicagoLIBRARY" 
    ["db_name"]=> string(15) "uchicagoLIBRARY" 
    ["yearpages"]=> string(5) "33391" 
    ["monthpages"]=> string(4) "2498" 
    ["daypages"]=> NULL 
    ["weekpages"]=> NULL } 

Array ( 
    [0] => station_name 
    [1] => db_name 
    [2] => yearpages 
    [3] => monthpages 
    [4] => daypages 
    [5] => weekpages 

---

查询没有处理daypages和weekpages，但monthpages和yearpages没有问题的原因是什么？

在使用case语句时，您应该按如下顺序保留日、周、月、年，以获得日和周

     $select2 = "SELECT IF( station_name =  '',  'Unknown', station_name ) 
                station_name, station_name as db_name, sum(case when 
     (day(print_date) = $day and year(print_date) = $year and  
     month(print_date) = $month) then print_pages end) as daypages, sum(case
     when (week(print_date) = $week AND year(print_date) = $year AND 
     month(print_date) = $month) then print_pages end) as weekpages, 
     sum(case when (month(print_date) = $month and year(print_date) = $year) 
     then print_pages end) as monthpages,sum(case when year(print_date) = 
     $year then print_pages end) as yearpages
                FROM `file_prints`
                GROUP BY station_name;";

---

首先，我希望您在执行查询之前转义了变量，因为您当前的实现可能面临sql注入攻击的风险

由于各种原因，这些值可能为空：

---

你能告诉我更多关于变量的值吗？您的

$day

和

$week

变量可能不是数值。或者您的表中没有

print_date

值等于

$day

或

$week

的行，我之前已将它们回显出来，可以确认$day和$week都是数字。我还在phpmyadmin中手动检查了最后一段的后半部分，但该参数不成立。对不起，请仔细检查：您发现的打印日期值等于

$day

，这些行是否也满足：

day（打印日期）=$day和year（打印日期）=$year和year（打印日期）=$year和month（打印日期）=$month）

？