无法从键JSON MySQL PHP获取值

CREATE TABLE example (
    id INT AUTO_INCREMENT PRIMARY KEY,
    data JSON
);

SELECT JSON_EXTRACT(data, '$.key1') AS key1_value FROM example WHERE id = 1;

<?php
// 假设$result是从数据库获取的结果集
$row = mysqli_fetch_assoc($result);
$jsonData = $row['data'];

// 解码JSON数据
$data = json_decode($jsonData, true);

// 获取特定键的值
$key1Value = $data['key1'];
echo $key1Value;
?>

<?php
$conn = new mysqli("localhost", "username", "password", "database");

$jsonData = json_encode(array("key1" => "value1", "key2" => "value2"));
$sql = "INSERT INTO example (data) VALUES (?)";
$stmt = $conn->prepare($sql);
$stmt->bind_param("s", $jsonData);
$stmt->execute();
?>

<?php
$conn = new mysqli("localhost", "username", "password", "database");

$sql = "SELECT JSON_EXTRACT(data, '$.key1') AS key1_value FROM example WHERE id = 1";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    echo "Key1 Value: " . $row['key1_value'];
} else {
    echo "No results found";
}
$conn->close();
?>