PHP使用PDO操作mysql读取数据步骤详解

$dbh = new \PDO($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; $newLine = PHP_SAPI == 'cli' ? "\n" : '
'; foreach ($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id 804288 消耗内存："0.34918212890625M 处理数据行数：254062 success