How can one effectively troubleshoot issues with mysqli_query in PHP?

Issue: When using mysqli_query in PHP, it is important to ensure that the connection to the database is properly established before executing the query. If there are any errors in the query syntax or connection, mysqli_query may return false, leading to issues in fetching data from the database. To troubleshoot issues with mysqli_query, check the connection status, verify the query syntax, and handle any errors that may occur during the query execution. 

// Establish a connection to the database
$mysqli = new mysqli("localhost", "username", "password", "database");

// Check if the connection is successful
if ($mysqli->connect_error) {
    die("Connection failed: " . $mysqli->connect_error);
}

// Define the query
$query = "SELECT * FROM table_name";

// Execute the query
$result = $mysqli->query($query);

// Check if the query was successful
if ($result) {
    // Process the data fetched from the database
    while ($row = $result->fetch_assoc()) {
        // Do something with the data
    }
} else {
    // Handle any errors that occurred during the query execution
    echo "Error: " . $mysqli->error;
}

// Close the connection
$mysqli->close();

Keywords

mysqli_query troubleshooting PHP error handling debugging

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