Paging program design understanding page. class. php

Paging program design understanding page. class. php about paging program, I understand that when a link such as [Next page] is clicked, the corresponding data on the next page is displayed.

This is essentially a database operation. Simply put, the SQL statement is the select some_fields from table limit Offset Num;

Here, Num is fixed. for example, 10 data entries are displayed on each page.

The key is Offset, that is, the Offset. this value changes every time you click the next page, for example, 10 ....

There are only two things finally displayed on the page. one is the corresponding data (images, text, etc ...), one is a paging link (xx records are displayed in total, 10 records are displayed on each page. Currently, page 1/32 [Homepage] [Previous Page] [Next Page] [last Page])

The specific implementation code below

 Count = $ count; $ this-> meiye = $ meiye; $ this-> pages = ceil ($ this-> count/$ this-> meiye ); $ this-> now_page = $ this-> get_now_page (); $ this-> url = $ url; $ this-> prev = $ this-> get_prev_page (); $ this-> next = $ this-> get_next_page (); $ this-> offset = $ this-> get_offset (); $ this-> style = $ this-> get_style ($ style);} // Obtain the current page private function get_now_page () {return isset ($ _ GET ['Page'])? $ _ GET ['Page']: 1;} // GET the previous page private function get_prev_page () {return $ this-> now_page-1? $ This-> now_page-1: false;} // get the next page private function get_next_page () {return $ this-> now_page + 1> $ this-> pages? False: $ this-> now_page + 1;} // Get the offset private function get_offset () {return $ this-> now_page <= 1 & $ this-> now_page> 0? 0 :( $ this-> now_page-1) * ($ this-> meiye);} // get paging link style default: // 30 records in total, 4 records per page, current page 1/8 [Homepage] [Next Page] [last Page] private function get_style ($ s) {$ str = ''; if ($ this-> pages> 1) {if ($ s = 1) {$ str. = "{$ this-> count} records in total, {$ this-> meiye} records per page, current page {$ this-> now_page}/{$ this-> pages} "; $ str. = "url? Page = 1'> [Homepage] "; $ this-> prev? $ Str. = "url? Page = $ this-> prev '> [previous page] ": false; $ this-> next? $ Str. = "url? Page = $ this-> next '> [next page] ": false; $ str. =" url? Page = $ this-> pages '> [last page] ";} else {$ str. = "current page {$ this-> now_page}/{$ this-> pages}"; $ str. = "url? Page = 1'> [Homepage] "; $ this-> prev? $ Str. = "url? Page = $ this-> prev '> [previous page] ": false; for ($ j = 1; $ j <= $ this-> pages; $ j ++) {$ str. = "url? Page = $ j> $ j ";}$ this-> next? $ Str. = "url? Page = $ this-> next '> [next page] ": false; $ str. =" url? Page = $ this-> pages '> [last page] ";}return $ str ;}}}

When used, get the Offset and style

 Acount (); // instantiate the paging class (total number of records, number of records displayed per page, execution script, style) $ p = new page ($ c, 4, 'page3. php ', 1); // Get the offset $ of = $ p-> offset; // query the database $ res = $ m-> select ('Pic ','', ''," $ of, 4 "); // convenient result set $ res // output paging link echo $ p-> style;