如何利用PHP函数进行数据分析和统计？

$data = [1, 2, 3, 4, 5];

// 计算数组元素的个数
$num = count($data);
echo "数组元素的个数：$num 
";

// 计算数组元素的和
$sum = array_sum($data);
echo "数组元素的和：$sum 
";

// 计算数组元素的平均值
$average = array_sum($data) / $num;
echo "数组元素的平均值：$average 
";

// 查找数组中的最大值和最小值
$max = max($data);
$min = min($data);
echo "数组中的最大值：$max 
";
echo "数组中的最小值：$min 
";

$string = 'Hello, world!';

// 计算字符串的长度
$length = strlen($string);
echo "字符串的长度：$length 
";

// 查找字符串是否包含某个子串
$substr = 'world';
$isFound = strpos($string, $substr);
if ($isFound !== false) {
    echo "字符串中包含子串：$substr 
";
} else {
    echo "字符串中不包含子串：$substr 
";
}

// 连接数据库
$host = 'localhost';
$dbname = 'test';
$user = 'root';
$pass = 'root';
$conn = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);

// 查询数据
$sql = "SELECT * FROM users";
$stmt = $conn->query($sql);
$data = $stmt->fetchAll(PDO::FETCH_ASSOC);

// 统计数据
$num = count($data);
echo "数据行数：$num 
";

// 数据分析
$totalAge = 0;
foreach ($data as $row) {
    $totalAge += $row['age'];
}
$averageAge = $totalAge / $num;
echo "平均年龄：$averageAge 
";

// 关闭数据库连接
$conn = null;