php + mysql 分页

<?php
	require_once 'db.php';

	$pageNow = 1;//当前页
	$pageSize = 5;//一页多少行
	$lineCount = 0;//总记录书
	$pageCount = 0;//总页数
	
	if(isset($_GET['pageNow'])){
		$pageNow = $_GET['pageNow'];
	}
	
	$sql = "select count(*) as count from channel_package";
	$res=$conn->query($sql);
	while($row=$res->fetch_assoc()){
		$lineCount = $row['count'];
	}
	$pageCount = ceil($lineCount/$pageSize);
	$sql = "select * from channel_package limit ".($pageNow-1) * $pageSize.", $pageSize";
	$res=$conn->query($sql);
	$data = array();
	while($row=$res->fetch_assoc()){
		array_push($data,array(
			"id"		=>	$row['id'],
			"id_string"	=>	$row['id_string'],
		));
	}
	echo json_encode(array("data"=>$data));
?>