What are the best practices for handling data types when performing calculations in PHP from SQL queries?

When performing calculations in PHP from SQL queries, it is important to handle data types properly to avoid unexpected results or errors. One common issue is when retrieving data from a database, it may be stored as a string instead of a numeric type, leading to incorrect calculations. To solve this, you can explicitly cast the data to the correct type before performing calculations. 

// Example SQL query to retrieve a numeric value
$sql = "SELECT SUM(amount) AS total FROM transactions";

// Execute the query and fetch the result
$result = $conn->query($sql);
$row = $result->fetch_assoc();

// Cast the result to a float before using it in calculations
$total = (float) $row['total'];

// Perform calculations with the numeric value
$tax = $total * 0.10;
$finalTotal = $total + $tax;

echo "Total amount: $total";
echo "Tax: $tax";
echo "Final total: $finalTotal";

Keywords

data types calculations PHP SQL queries handling

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