mysql 动态条件查询

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 获取用户输入的查询条件
$name = $_GET['name'] ?? '';
$age = $_GET['age'] ?? '';

// 构建动态查询语句
$sql = "SELECT * FROM users WHERE 1=1";
$params = [];

if (!empty($name)) {
    $sql .= " AND name LIKE ?";
    $params[] = "%$name%";
}

if (!empty($age)) {
    $sql .= " AND age = ?";
    $params[] = $age;
}

// 执行查询
$stmt = $conn->prepare($sql);
$stmt->bind_param(str_repeat("s", count($params)), ...$params);
$stmt->execute();
$result = $stmt->get_result();

// 处理查询结果
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "ID: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
    }
} else {
    echo "0 结果";
}

// 关闭连接
$stmt->close();
$conn->close();
?>