PHP paging principle example analysis

/*
author: silently
date :2006-12-03
*/
$page=isset($_get['page'])?intval($ _get['page']):1; //This sentence is to get the value of page in page=18. If page does not exist, then the page number is 1.
$num=10; //Display 10 pieces of data per page
$db=mysql_connect("host","name","pass"); //Create a database connection
$select=mysql_select_db("db",$db ); //Select the database to operate
/*
First, you need to get how much data there is in the database to determine how many pages it needs to be divided into. The specific formula for the total number of pages is
The total number of data divided by the items displayed on each page Count, if there is more than one, add one.
That is to say, 10/3=3.3333=4. If there is a remainder, we must round it up by one.
*/
$total=mysql_num_rows(mysql_query("select * from table")); //The total number of query data total
$pagenum=ceil($total/$num); //Get the total number of pages pagenum
// If the page number parameter apge passed in is greater than the total page number pagenum, an error message will be displayed
if($page>$pagenum || $page == 0){
 echo "error : can not found the page .";
 exit ;
}
$offset=($page-1)*$num; //Get the value offset of the first parameter of limit. If the first page is (1-1)*10=0, the second page is (2-1)*10=10.
//(Number of pages passed in -1) * The data of each page gets the value of the first parameter of limit
$info=mysql_query("select * from table limit $offset,$num "); //Get the corresponding page Count the data to be displayed
while($it=mysql_fetch_array($info)){
 echo $it['name']."";
} //Display data
 for($i=1;$i<=$pagenum;$i++){
 $show=($i!=$page)?"$i":"$i";
 echo $show." ";
}
/* Display paging information. If it is the current page, bold numbers will be displayed. The remaining page numbers are hyperlinks. If it is the third page, it will be displayed as follows
1 2 3 4 5 6
*/
?>

Summary: prototype: select * from table limit 0,10

Procedure:

select * from user order by id desc limit 0,10;