mysql sql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);
}

// 初始化查询条件
$whereClause = "";
$params = [];

// 动态添加条件
if (!empty($_GET['name'])) {
    $whereClause .= "name = ? AND ";
    $params[] = $_GET['name'];
}
if (!empty($_GET['age'])) {
    $whereClause .= "age = ? AND ";
    $params[] = $_GET['age'];
}

// 移除最后一个 "AND"
if (!empty($whereClause)) {
    $whereClause = rtrim($whereClause, " AND ");
}

// 构建完整的SQL查询
$sql = "SELECT * FROM users";
if (!empty($whereClause)) {
    $sql .= " WHERE " . $whereClause;
}

$stmt = $conn->prepare($sql);

// 绑定参数
foreach ($params as $key => $value) {
    $stmt->bind_param("s", $value); // 假设所有参数都是字符串类型
}

$stmt->execute();
$result = $stmt->get_result();

// 输出结果
while ($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
}

$stmt->close();
$conn->close();
?>