PDO::execute 的 pgsql 42601 错误

Question

我遇到了 $pdo->execute($values) 的问题。

如果我在没有 $values 的情况下使用 $pdo->execute()，它可以正常工作：

$dsn = sprintf('%s:host=%s;port=%s;dbname=%s', DB_TYPE, DB_HOST, DB_PORT, DB_NAME);
$pdo = new PDO($dsn, DB_USER, DB_PASS, array());
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$sql = 'SELECT * FROM "user" ORDER BY id DESC LIMIT 50 OFFSET 0';
$stmt = $pdo->prepare(trim($sql));
$stmt->setFetchMode(PDO::FETCH_OBJ|PDO::FETCH_PROPS_LATE);
$stmt->execute();

echo "<pre>";
print_r($stmt->fetchAll());
echo "</pre>";

它工作正常，但是当我想添加值替换时：

$dsn = sprintf('%s:host=%s;port=%s;dbname=%s', DB_TYPE, DB_HOST, DB_PORT, DB_NAME);
$pdo = new PDO($dsn, DB_USER, DB_PASS, array());
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$sql = 'SELECT * FROM "user" ORDER BY ? ? LIMIT 50 OFFSET 0';
$values = array('id','DESC');

$stmt = $pdo->prepare(trim($sql));
$stmt->setFetchMode(PDO::FETCH_OBJ|PDO::FETCH_PROPS_LATE);
$stmt->execute($values);

echo "<pre>";
print_r($stmt->fetchAll());
echo "</pre>";

它不起作用。它返回：

SQLSTATE[42601]：语法错误：7 错误：“$2”或附近的语法错误 第 1 行：SELECT * FROM "user" ORDER BY $1 $2 LIMIT 50 OFFSET 0 ^' in ...

Answer 1

如果 order by 子句中有多个列，ORDER BY 需要一个以逗号分隔的列列表