What strategies can be used to troubleshoot and debug PHP code effectively, especially when dealing with issues related to variable assignment and data retrieval?

Issue: When dealing with variable assignment and data retrieval in PHP, it's important to ensure that the correct variable is being assigned the expected value and that data is being retrieved accurately from the source. Solution: To troubleshoot and debug PHP code effectively in these scenarios, you can use techniques such as printing out the values of variables using `var_dump()` or `print_r()`, checking for typos in variable names, verifying the data source (such as a database query or API response), and using conditional statements to validate the values being assigned or retrieved. PHP Code Snippet:

// Example of troubleshooting variable assignment and data retrieval
$variable = "example";

// Print out the value of the variable to check its contents
var_dump($variable);

// Check for typos in variable names and correct if necessary
$correct_variable = "example";

// Retrieve data from a database query
$query = "SELECT * FROM table";
$result = mysqli_query($connection, $query);

// Check if the query was successful and fetch the data
if($result) {
    $data = mysqli_fetch_assoc($result);
    var_dump($data);
} else {
    echo "Error retrieving data from database.";
}