如何在php中访问查询结果的密钥对值

$conn = new mysqli("localhost", "username", "password", "database");
$query = "SELECT key_column, value_column FROM table_name";
$result = $conn->query($query);

while ($row = $result->fetch_assoc()) {
    $key = $row['key_column'];
    $value = $row['value_column'];
    // 处理密钥对值
}

$data = array();
while ($row = $result->fetch_assoc()) {
    $key = $row['key_column'];
    $value = $row['value_column'];
    $data[$key] = $value;
}

// 使用密钥对值
echo $data['key1']; // 输出密钥为'key1'的值