PHP使用PDO从mysql读取大量数据处理详解

$dbh = new /PDO($dsn, $user, $pass);# 关键设置，如果不设置，php依旧会从pdo一次取出数据到php$dbh->setAttribute(/PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);//perpare里的游标属性不是必须的$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';  //数据库类型  $host=C('DB_HOST'); //数据库主机名  $dbName=C('DB_NAME'); //使用的数据库  $user=C('DB_USER');  //数据库连接用户名  $pass=C('DB_PWD');   //对应的密码  $dsn="$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 "消耗内存：" . (memory_get_usage() / 1024 / 1024) . "M" . $newLine;  echo "处理数据行数：" . $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id804288消耗内存："0.34918212890625M处理数据行数：254062success