pgsql 42601錯誤與PDO ::執行

Question

我有$ pdo-> execute（$ values）的問題。

如果我用$pdo->execute()它工作正常，無$值：

$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，但是當我要添加值替換：

$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>"; 

它不工作。它返回：

SQLSTATE[42601]: Syntax error: 7 ERROR: syntax error at or near "$2" LINE 1: SELECT * FROM "user" ORDER BY $1 $2 LIMIT 50 OFFSET 0 ^' in ...

Answer 1

ORDER BY需要一個逗號分隔的列清單，如果當你execute與參數的問號被轉義值替換有順序多列BY子句

Answer 2

。在這種情況下，值不應該被轉義（因爲它們是字段名稱/保留字）。

我認爲在這種情況下，簡單的解決方案是串聯的字段名稱：

$field = 'id'; 
$ord = 'DESC'; 

$sql = "SELECT * FROM user ORDER BY $field $ord LIMIT 50 OFFSET 0'; 
// prepare... 
$stmt->execute();