What are common logic errors when trying to store query results in PHP variables?

Common logic errors when trying to store query results in PHP variables include not properly fetching the results from the query, not checking if the query was successful before trying to store the results, and not handling cases where the query returns no results. To solve this, always check the query result before trying to store it in variables, handle cases where the query returns no results, and ensure the correct method is used to fetch the results. 

// Assume $conn is the database connection object

// Execute the query
$query = "SELECT * FROM users";
$result = $conn->query($query);

// Check if the query was successful
if ($result) {
    // Check if there are any results
    if ($result->num_rows > 0) {
        // Fetch and store the results in variables
        while ($row = $result->fetch_assoc()) {
            $username = $row['username'];
            $email = $row['email'];
            // Process the results as needed
        }
    } else {
        echo "No results found.";
    }
} else {
    echo "Error executing query: " . $conn->error;
}

Keywords

SQL injection mysqli_fetch_array data type mismatch empty result set error handling

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