English
English
In PHP development, data accuracy and type validation are crucial when handling database query results. This is especially important when dealing with numeric data, as confirming whether the data is a floating-point number (real number) can effectively prevent subsequent calculation errors or logical flaws. This article will explain how to use the custom is_real() function to validate query results and ensure data correctness.
Data returned from database queries is typically in string format, whether it's an integer, floating-point number, or text. Using this data directly in mathematical calculations or logical comparisons may lead to unexpected results due to type conversion. For example:
$value = "123.45"; // This is a string
$result = $value + 10; // PHP will automatically convert, but there are potential risks
To avoid issues caused by implicit type conversion, it is recommended to validate the data type before using the data.
PHP does not have a built-in is_real() function, but we can use regular expressions or the filter_var function to determine whether a variable is a floating-point number.
Example code:
function is_real($value) {
// Use filter_var to check if it's a valid floating-point number
return filter_var($value, FILTER_VALIDATE_FLOAT) !== false;
}
This function will return a boolean value indicating whether the provided $value is a valid floating-point number.
Suppose we query a record from the database and retrieve a field price. We want to verify if it is a floating-point number before proceeding with further operations.
<?php
// Example of database connection
$mysqli = new mysqli("m66.net", "username", "password", "database");
<p>// Query data<br>
$sql = "SELECT price FROM products WHERE id=1";<br>
$result = $mysqli->query($sql);</p>
<p>if ($result) {<br>
$row = $result->fetch_assoc();<br>
$price = $row['price'];</p>
if (is_real($price)) {
echo "The price is a valid floating-point number, value: $price";
// Safe to use $price for calculations
$discounted = $price * 0.9;
echo "Discounted price: $discounted";
} else {
echo "The price is not a valid floating-point number, please check the data source.";
}
} else {
echo "Query failed: " . $mysqli->error;
}
?>
Using the custom is_real() function to validate data types in database query results is an effective way to ensure data correctness and avoid logical errors. Especially when dealing with floating-point operations and financial calculations, always perform data validation to safeguard the program's robustness and security from the start.
