[英]calculate distance between 2 points using php and mysql
我有一個表格,允許用戶從數據庫中選擇第一個地點的城市名稱,然后選擇第二個地點的城市名稱,然后提交計算按鈕
村表包含:
我在我的代碼中做到了這一點,但沒有顯示任何內容,而var_dump顯示為null
誰能幫我 ?????
<?php
if(isset($_POST['calculate']))
{
$pt1 = $_POST['pt1'];
$pt2 = $_POST['pt2'];
$sql = mysql_query("SELECT longitude, lattitude FROM village WHERE id = '$pt1' AND id = '$pt2'")or die(mysql_error());
$num_row = mysql_num_rows($sql);
if($num_row > 0)
{
while($row = mysql_fetch_array($sql))
{
$lon_s = $row['longitude'];
$lon_e = $row['longitude'];
$lat_s = $row['lattitude'];
$lat_e = $row['lattitude'];
var_dump($lon_e);
var_dump($lon_s);
var_dump($lat_e);
var_dump($lat_s);
$R = 6371; //km
$A = pow(sin(($lat_e - $lat_s)/2), 2) + cos($lat_s) * cos($lat_e) * pow(sin(($lon_e - $lon_s)/2) , 2);
$C = 2 * atan2(sqrt($A), sqrt(1 - $A));
$D = $R * $C;
echo $D;
}
}
}
<table width="30%" border="3" align="right">
<form action="map.php" method="post">
<tr>
<td width="37%"> Location one: </td>
<td width="63%"><select id="location1" name="pt1">
<?php echo $opt->Showlocation() ?>
</select>
<br /></td>
</tr>
<tr>
<td>Location two:</td>
<td><select id="location2" name="pt2">
<option value="0">choose...</option>
</select></td>
</tr>
<tr>
<td> </td>
<td><input type="submit" name="calculate" value="Calculate Distance" /></td>
</tr>
</form>
</table>
這是因為WHERE id = '$pt1' AND id = '$pt2'
你應該在WHERE clause
上有1
WHERE id = '$pt1'
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