How to Use PHP mysqli_num_rows to Get the Number of Rows in a Result Set

When working with databases in PHP, you may need to know how many rows a query returned; the mysqli_num_rows function provides a convenient way to obtain this count.

connect_errno) {
    echo "Failed to connect to database: " . $mysqli->connect_error;
    exit;
}

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

// Verify query success
if (!$result) {
    echo "Query failed: " . $mysqli->error;
    exit;
}

// Get number of rows in result set
$num_rows = mysqli_num_rows($result);

// Output the count
echo "Number of rows in result set: " . $num_rows;

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

In the example, the script connects to the MySQL server, runs a SELECT statement, checks for errors, uses mysqli_num_rows to retrieve the row count stored in $num_rows , and echoes the result.

Note that mysqli_num_rows should only be called after a successful query; if the query fails, the result set is empty and the function returns 0.

Using mysqli_num_rows is a practical technique for determining whether data was returned and for counting rows in database operations.