mysql多条件查询为空处理

SELECT * FROM users WHERE age > ? AND city = ?;

SELECT * FROM users WHERE age > COALESCE(?, 0) AND city = COALESCE(?, '');

$sql = "SELECT * FROM users WHERE 1=1";
$params = [];

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

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

// 执行查询
$stmt = $pdo->prepare($sql);
$stmt->execute($params);
$result = $stmt->fetchAll();

$query = DB::table('users');

if (!empty($age)) {
    $query->where('age', '>', $age);
}

if (!empty($city)) {
    $query->where('city', '=', $city);
}

$result = $query->get();

<?php
$pdo = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');

$age = isset($_GET['age']) ? $_GET['age'] : null;
$city = isset($_GET['city']) ? $_GET['city'] : null;

$sql = "SELECT * FROM users WHERE 1=1";
$params = [];

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

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

$stmt = $pdo->prepare($sql);
$stmt->execute($params);
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);

print_r($result);
?>