php - 尝试从时间戳按月总计

我试图按月从mysql上获取读数的总和，并且日期在sql文件的日期时间戳字段中。

<?php
$db = new mysqli('localhost', 'php06', 'php06', 'php00');

if (mysqli_connect_errno()) {
  echo "Error: Could not connect to database.  Please try again later.";
  exit;}

$query = "select readingVolume, readingDate from Reading order by readingDate";
$result = $db->query($query);
while($row = $result->fetch_assoc()){
$mysqldate = $row['readingDate'];
$timestamp = strtotime($mysqldate);
$day = date("d", $timestamp);
$month = date("m", $timestamp);
$year = date("Y", $timestamp);

if ($month = 01){
$JanRead = ($row['readingVolume'] + $JanRead);}
if ($month = 02){
$FebRead = ($row['readingVolume'] + $FebRead);}
if ($month = 03){
$MarRead = ($row['readingVolume'] + $MarRead);}
if ($month = 04){
$AprRead = ($row['readingVolume'] + $AprRead);}
if ($month = 05){
$MayRead = ($row['readingVolume'] + $MayRead);}
if ($month = 06){
$JunRead = ($row['readingVolume'] + $JunRead);}
if ($month = 07){
$JulRead = ($row['readingVolume'] + $JulRead);}
if ($month = 08){
$AugRead = ($row['readingVolume'] + $AugRead);}
if ($month = 09){
$SepRead = ($row['readingVolume'] + $SepRead);}
if ($month = 10){
$OctRead = ($row['readingVolume'] + $OctRead);}
if ($month = 11){
$NovRead = ($row['readingVolume'] + $NovRead);}
if ($month = 12){
$DecRead = ($row['readingVolume'] + $DecRead);}
}

$readingarray = array($JanRead,$FebRead,$MarRead,$AprRead,$MayRead,
                        $JunRead,$JulRead,$AugRead,$SepRead,$OctRead,
                        $NovRead,$DecRead);
print_r($readingarray);
?>

最佳答案

您的主要问题似乎是应该使用=时使用==进行相等性测试。并且除非在进行字符串比较并且数字带有前缀（例如0或$foo == 1），否则不要在$foo == '01之前加整数。

如果您直接插入数组，则可以使其更短：

$readingarray[$month] += $row['readingVolume'];

另外请注意，如果您按月份分组并执行SUM()，则可以通过MySQL进行此查询。如果您的字段是日期类型，那将是微不足道的。作为UNIX时间戳，您首先需要将其转换为日期。 （一个额外的MySQL函数调用。）

关于php - 尝试从时间戳按月总计，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/4418788/