当前行和上一行之间的MySQL视图和数学

Question

我正在从太阳能充电控制器收集数据到MySQL数据库（5.5.52）。到目前为止，我有一个TABLE，寄存器：

mysql> SELECT date,time,panelVoltage,panelCurrent,batteryVoltage,loadCurrent
  FROM registers
  ORDER BY date,time
  LIMIT 4;
+------------+----------+--------------+--------------+----------------+-------------+
| date       | time     | panelVoltage | panelCurrent | batteryVoltage | loadCurrent |
+------------+----------+--------------+--------------+----------------+-------------+
| 2016-11-27 | 17:20:41 |        26.04 |         1.31 |          25.15 |        0.72 |
| 2016-11-27 | 17:21:06 |        26.06 |         1.31 |          25.15 |        0.76 |
| 2016-11-27 | 17:21:32 |        26.06 |         1.15 |          25.16 |         0.6 |
| 2016-11-27 | 17:21:57 |        26.06 |          1.3 |          25.16 |        0.68 |
+------------+----------+--------------+--------------+----------------+-------------+

我想计算面板的瓦特小时数并加载为我认为的VIEW，因此它保持最新。 （非常）伪代码：

SELECT (panelVoltage * panelCurrent) as panelWattage,
  CONCAT(date, ' ', time) AS datetime
  FROM registers ORDER BY datetime;
timeDiff = (currRow.datetime from prevRow.datetime)/3600 # for time decimal hours
powerSum = (currRow.panelWattage + prevRow.panelWattage)/2 # for average Wattage
Wh = timeDiff * powerSum # for Watt-hours

因此，视图/列将包含panelWh和loadWh，并且可能是每个panelWhSum，loadWhSum的运行总和。

这是我的PHP代码就是这样 - 我理解一个视图会更有效：

  $qry = "SELECT CONCAT(date,' ',time) as datetime,loadCurrent,batteryVoltage,panelCurrent,panelVoltage,
    panelCurrent * panelVoltage as 'panelWatt', loadCurrent * batteryVoltage as 'loadWatt' FROM registers
    WHERE TIMESTAMP(`date`, `time`) > NOW() - INTERVAL ".$_GET['time']." MINUTE";
  $result = mysqli_query($con,$qry);
  $table = array();
  $table['cols'] = array(
    array('label' => 'datetime', 'type' => 'datetime'),
    array('label' => 'panel Wh', 'type' => 'number'),
    array('label' => 'load Wh', 'type' => 'number'),
    array('label' => 'net Wh', 'type' => 'number')
  foreach($result as $row){
    $prevTime = $curTime;
    $curTime = $datetime;
    $prevPW = $curPW;
    $curPW = $row['panelWatt'];
    $prevLW = $curLW;
    $curLW = $row['loadWatt'];
    if ($i == 0) {
      $prevTime = $datetime;
      $prePW = $row['panelWatt'];
      $preLW = $row['loadWatt'];
    }
    $diffInSeconds = $curTime->getTimestamp() - $prevTime->getTimestamp();
    $panelWh = ($diffInSeconds * 0.5 * ($prevPW + $curPW) / 3600);
    $panelWhTotal = $panelWhTotal + $panelWh;
    $loadWh = ($diffInSeconds * 0.5 * ($prevLW + $curLW) / 3600);
    $loadWhTotal = $loadWhTotal + $loadWh;
    $temp[] = array('v' => (float) round($panelWhTotal, 2));
    $temp[] = array('v' => (float) round($loadWhTotal, 2));
    $temp[] = array('v' => (float) round(($panelWhTotal - $loadWhTotal), 2));
  }

以上PHP代码中的示例： panel, load Watt-hours

Answer 1

我建议您使用如下表格。看到我有单独的数据和时间列。它帮助我做一个你想要的图形