What are the implications of querying a database for a non-existent value in PHP and how can it be handled effectively?

When querying a database for a non-existent value in PHP, it can return an empty result set or NULL, depending on the database driver used. To handle this effectively, you can check if the query returned any results before trying to access them to prevent errors in your code. 

// Query the database
$result = mysqli_query($connection, "SELECT * FROM table WHERE id = 123");

// Check if any results were returned
if(mysqli_num_rows($result) > 0) {
    // Fetch the data
    $row = mysqli_fetch_assoc($result);
    // Process the data
} else {
    // Handle the case where no results were found
    echo "No results found.";
}

Keywords

database query PHP error handling SQL exception handling

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