我需要将 ProductID 的值和成本相除。
下面是我的代码示例：
<?php
$servername = "localhost";
$username = "root";
$password = "root";
$dbname = "testting";
$a = "calculationexample.ProductID";
$b = "calculationexample.Cost";
$c = "(a/b)";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "INSERT INTO calculationexample (ProductID, Cost, Ratio)
VALUES ('400', '200', '$c')";
// use exec() because no results are returned
$conn->exec($sql);
echo "New record created successfully";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
为"产品 ID"、"成本"字段（比率除外）字段正确插入该值。谁能告诉我正确的方法？
谢谢。
=== 问题已更新 ====
<?php
require 'database.php';
if ( !empty($_POST)) {
// keep track validation errors
$ProductIDError = null;
$CostError = null;
$MonthError = null
// keep track post values
$ProductID = $_POST['ProductID'];
$Cost = $_POST['Cost'];
$Month = $_POST['Month'];
// validate input
$valid = true;
if (empty($ProductID)) {
$ProductIDError = 'Please enter product id';
$valid = false;
}
$valid = true;
if (empty($Cost)) {
$CostError = 'Please enter cost value';
$valid = false;
}
$valid = true;
if (empty($Month)) {
$MonthError = 'Please enter cost value';
$valid = false;
}
$conn= new PDO("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
//$var = "John"; // based on an id column (varchar)
$stmt = $conn->prepare('SELECT Month,ProductID,Cost,Ratio FROM Inventory');
// $stmt->bindValue(1, $var);
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$a = $row['ProductID'];
$b = $row['Cost'];
$m =$row['Month']
$c = ($a/$b);
//echo $c; // will output the ratio
}
}
try {
$stmt = $conn->prepare("INSERT INTO Inventory
(Month,ProductID, Cost, Ratio)
VALUES(:Month, :ProductID, :Cost, :Ratio)");
$stmt->bindValue(':Month', $m,PDO::PARAM_INT);
$stmt->bindValue(':ProductID', $a,PDO::PARAM_INT);
$stmt->bindValue(':Cost', $b,PDO::PARAM_INT);
$stmt->bindValue(':Ratio', $c,PDO::PARAM_INT);
$stmt->execute();
echo "New record created successfully";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<link href="css/bootstrap.min.css" rel="stylesheet">
<script src="js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<div class="span10 offset1">
<div class="row">
<h3>Inventory</h3>
</div>
<form class="form-horizontal" action="division.php" method="post">
<div class="control-group <?php echo !empty($MonthError)?'error':'';?>">
<label class="control-label">Month</label>
<div class="controls">
<input name="month" type="text" placeholder="Month" value="<?php echo !empty($m)?$m:'';?>">
<?php if (!empty($MonthError)): ?>
<span class="help-inline"><?php echo $MonthError;?></span>
<?php endif; ?>
</div>
</div>
<div class="control-group <?php echo !empty($ProductID)?'error':'';?>">
<label class="control-label">ProductID</label>
<div class="controls">
<input name="ProductID" type="text" placeholder="ProductID" value="<?php echo !empty($ProductID)?$ProductID:'';?>">
<?php if (!empty($ProductIDError)): ?>
<span class="help-inline"><?php echo $ProductIDError;?></span>
<?php endif;?>
</div>
</div>
<div class="control-group <?php echo !empty($Cost)?'error':'';?>">
<label class="control-label">Cost</label>
<div class="controls">
<input name="Cost" type="text" placeholder="Cost" value="<?php echo !empty($Cost)?$Cost:'';?>">
<?php if (!empty($CostError)): ?>
<span class="help-inline"><?php echo $CostError;?></span>
<?php endif;?>
</div>
</div>
<div class="form-actions">
<button type="submit" class="btn btn-success">Daftar</button>
<a class="btn" href="index.bulanan.php">Menu Utama</a>
</div>
</form>
</div>
</div> <!-- /container -->
</body>
</html>
您首先需要做的是查询数据库，以便从"产品 ID"和"成本"列中获取值，以便能够获取要在表中输入的比率。
正如我在评论区域中概述的那样，您需要将$c = "(a/b)";更改为$c = ($a/$b);
就目前而言，"a"和"b"都被视为常量，并在引号内设置时被视为字符串。
如果在引号内设置，$c = "($a/$b)";将产生 （10/50），而$c = ($a/$b);将根据使用$a = 10; $b = 50;生成 0.2
要采取的步骤：
- 查询您的表
- 计算列中的值（必须是整数）
- 将查询表中的结果值插入到所需表中
旁注：不确定 400 和 200 ('400', '200', '$c')在那里做什么，以及这些是否是您希望用作比率的数字。您可能需要详细说明。
您的比率列需要为十进制 50，2/50 是一个夸张的数字，但 2 将是小数点。
注意：比率会产生小数。
附加说明：下面的$var = "John";基于id列（VARCHAR）
例如：
<?php
$mysql_hostname = 'xxx'; // change
$mysql_username = 'xxx'; // to
$mysql_password = 'xxx'; // your
$mysql_dbname = 'xxx'; // own
$conn= new PDO("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$var = "John"; // based on an id column (varchar)
$stmt = $conn->prepare('SELECT Cost, ProductID FROM calculationexample WHERE id = ?');
$stmt->bindValue(1, $var);
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$a = $row['Cost'];
$b = $row['ProductID'];
$c = ($a/$b);
echo $c; // will output the ratio
}
try {
$prod_id = 400;
$cost = 200;
$stmt = $conn->prepare("INSERT INTO calculationexample
(ProductID, Cost, Ratio)
VALUES(:prod_id, :cost, :ratio)");
$stmt->bindValue(':prod_id', $prod_id,PDO::PARAM_INT);
$stmt->bindValue(':cost', $cost,PDO::PARAM_INT);
$stmt->bindValue(':ratio', $c,PDO::PARAM_INT);
$stmt->execute();
echo "New record created successfully";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>