<?php
$pdo=new PDO('mysql:host=127.0.0.1;dbname=php','root','root');
$sql='select * from `staff` where `age`>:age';
$stmt=$pdo->prepare($sql);
//$stmt->bindValue('position','文化馆长',PDO::PARAM_STR);
//$stmt->bindValue('id',6,PDO::PARAM_INT);
$stmt->execute([':age'=>40]);
echo '记录数量是：'.$stmt->rowCount().'<br>';


$sql='select count(*) from `staff` where `age`>:age';
$stmt=$pdo->prepare($sql);
$stmt->execute([':age'=>40]);

if($stmt->fetchColumn(0)){
   $sql='select * from `staff` where `age`>:age';
   $stmt=$pdo->prepare($sql);
   $stmt->execute([':age'=>40]);
   foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $item) {
   echo '<pre>'.print_r($item,true);
   }
}
$pdo=null;