$dbh = new \PDO($dsn, $user, $pass);
# 關(guān)鍵設(shè)置，如果不設(shè)置，php依舊會從pdo一次取出數(shù)據(jù)到php
$dbh->setAttribute(\PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);
//perpare里的游標(biāo)屬性不是必須的
$sth = $dbh->prepare("SELECT * FROM `order`", array(\PDO::ATTR_CURSOR => \PDO::CURSOR_SCROLL));
$sth->execute();

class Test {
 public function test()
 {
  set_time_limit(0);
  $dbms='mysql';  //數(shù)據(jù)庫類型
  $host=C('DB_HOST'); //數(shù)據(jù)庫主機名
  $dbName=C('DB_NAME'); //使用的數(shù)據(jù)庫
  $user=C('DB_USER');  //數(shù)據(jù)庫連接用戶名
  $pass=C('DB_PWD');   //對應(yīng)的密碼
  $dsn="$dbms:host=$host;dbname=$dbName";
  $dbh = new \PDO($dsn, $user, $pass);
  $dbh->setAttribute(\PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);
  $sth = $dbh->prepare("SELECT * FROM `order`");
  $sth->execute();
  $i = 0;

  $newLine = PHP_SAPI == 'cli' ? "\n" : '<br />';

  foreach ($this->cursor($sth) as $row) {
//   var_dump($row);
   echo $row['id'] . $newLine;
   $i++;
  }

  echo "消耗內(nèi)存：" . (memory_get_usage() / 1024 / 1024) . "M" . $newLine;
  echo "處理數(shù)據(jù)行數(shù)：" . $i . $newLine;
  echo "success";
 }

 public function cursor($sth)
 {
  while($row = $sth->fetch(\PDO::FETCH_ASSOC)) {
   yield $row;
  }
 }
}

$test = new Test();
$test->test();

1
... //省略部分id
804288
消耗內(nèi)存："0.34918212890625M
處理數(shù)據(jù)行數(shù)：254062
success