来自MySQL行的数据乘法 [英] Multiplication of data from MySQL row

问题描述

我希望能够将所有价格乘以例如数据库中的价格，然后将总价格乘以10.

I would like to be able to multiply all the prices for example from my database then multiply the total by 10.

下面的代码执行加法运算而不是乘法运算

The code below do the addition not multiplication

<?php
$d = $_GET['d'];
$con = mysql_connect("localhost","username","password");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }
mysql_select_db("databasename", $con);//

$sql= "SELECT SUM(prices) FROM tablename WHERE Date = '$d' AND Prices >0.20 AND Type= 'sold'";
$results = mysql_query($sql);
$row = mysql_fetch_array($results);
echo $row[0]*10;


mysql_close($con);
?> 

示例

id prices
1   25
2   36
3   45

那是我想要25 * 36 * 45 * 10而不是25 + 36 + 45 * 10

That is i want 25*36*45*10 and not 25+36+45*10

希望任何人都可以帮助

推荐答案

这是可行的，但有限制(数字只能为正数):

This would work, with restrictions (numbers should be only positive):

SELECT 10 * EXP(SUM(LOG(prices))) AS result
FROM tablename 
WHERE ...

thnx应该转到 Napier ，他的精彩之处发明， logarithms

The thnx should go to Napier and his wonderful invention, logarithms

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