二维数组（getYieldArrays）

普通查询

$db = Be::getDb(); 

$sql = 'SELECT * FROM user WHERE age<18 AND sex=\'女\'';
$users = $db->getYieldArrays($sql);

foreach ($users as $user) {
   // $user['name'];
}

占位符查询

$db = Be::getDb(); 

$sql = 'SELECT * FROM user WHERE age<? AND sex=?';
$users = $db->getYieldArrays($sql,  [18, '女']);