如何在PHP中使用Oracle数据库的数据缓存和查询优化

CREATE TABLE cache_table (
    key VARCHAR2(100) PRIMARY KEY,
    value VARCHAR2(1000),
    expire_time DATE
);

$db_connection = oci_connect('username', 'password', 'localhost/XE');

// 查询缓存表
$cache_sql = "SELECT value FROM cache_table WHERE key = :key AND expire_time > SYSDATE";
$cache_statement = oci_parse($db_connection, $cache_sql);
oci_bind_by_name($cache_statement, ':key', $key);
oci_execute($cache_statement);

if ($cache_row = oci_fetch_array($cache_statement)) {
    $value = $cache_row['VALUE'];
} else {
    // 查询数据操作
    $data_sql = "SELECT * FROM data_table WHERE key = :key";
    $data_statement = oci_parse($db_connection, $data_sql);
    oci_bind_by_name($data_statement, ':key', $key);
    oci_execute($data_statement);
    
    // 取得查询结果
    $data_row = oci_fetch_array($data_statement);
    $value = $data_row['VALUE'];
    
    // 将查询结果存入缓存表
    $insert_sql = "INSERT INTO cache_table (key, value, expire_time) VALUES (:key, :value, SYSDATE + 3600)";
    $insert_statement = oci_parse($db_connection, $insert_sql);
    oci_bind_by_name($insert_statement, ':key', $key);
    oci_bind_by_name($insert_statement, ':value', $value);
    oci_execute($insert_statement);
}

oci_close($db_connection);

// 返回查询结果
echo $value;

// 连接到Memcached服务器
$memcached = new Memcached();
$memcached->addServer('localhost', 11211);

// 查询缓存数据
$value = $memcached->get($key);

if ($value === false) {
    // 查询数据操作
    $db_connection = oci_connect('username', 'password', 'localhost/XE');
    $data_sql = "SELECT * FROM data_table WHERE key = :key";
    $data_statement = oci_parse($db_connection, $data_sql);
    oci_bind_by_name($data_statement, ':key', $key);
    oci_execute($data_statement);
    
    // 取得查询结果
    $data_row = oci_fetch_array($data_statement);
    $value = $data_row['VALUE'];
    
    // 将查询结果存入缓存
    $memcached->set($key, $value, 3600);
    
    oci_close($db_connection);
}

// 返回查询结果
echo $value;