How PHP achieves webpage paging effect-php Tutorial

In the PHP website, there are many requirements for implementing pagination in PHP, which are mainly used to read novels.

The functions are as follows:

Several functions need to be called for paging using SQL queries. for details, see the script:
1. pager. class. php

Class pager {
Public $ SQL; // SQL query statement
Public $ datanum; // query the total number of data records
Public $ page_size; // number of records displayed on each page
Protected $ _ errstr;
Protected $ _ conn;
Protected $ _ query_id;

Public function query ($ query) // This function is faulty. you can skip this function for the moment.
{
$ Ret = false;
If (! Empty ($ query )){
If ($ this-> _ conn = false |! Is_resource ($ this-> _ conn )){
WarningLog (_ METHOD _. ': query SQL with no connection', true );
Return false;
}
$ This-> _ query_id = @ mysql_query ($ query, $ this-> _ conn );
If ($ this-> _ query_id === false ){
$ This-> _ errstr = @ mysql_error ();
$ Ret = false;
} Else {
$ This-> _ errstr = 'success ';
$ Ret = $ this-> _ query_id;
}
}
$ Msg = ($ ret = false )? 'False': strval ($ ret );
DebugLog (_ METHOD _. ": [$ msg] returned for SQL query [$ query]");
Return $ ret;
}
Function _ construct ($ SQL, $ page_size ){
$ Result = mysql_query ($ SQL );
$ Datanum = mysql_num_rows ($ result );
$ This-> SQL = $ SQL;
$ This-> datanum = $ datanum;
$ This-> page_size = $ page_size;
}

// Current page number
Public function page_id (){
If ($ _ SERVER ['query _ string'] = ""){
Return 1;
} Elseif (substr_count ($ _ SERVER ['query _ string'], "page_id =") = 0 ){
Return 1;
} Else {
Return intval (substr ($ _ SERVER ['query _ string'], 8 ));
}
}

// Remaining url value
Public function url (){
If ($ _ SERVER ['query _ string'] = ""){
Return "";
} Elseif (substr_count ($ _ SERVER ['query _ string'], "page_id =") = 0 ){
Return "&". $ _ SERVER ['query _ string'];
} Else {
Return str_replace ("page_id =". $ this-> page_id (), "", $ _ SERVER ['query _ string']);
}
}

// Total number of pages
Public function page_num (){
If ($ this-> datanum = 0 ){
Return 1;
} Else {
Return ceil ($ this-> datanum/$ this-> page_size );
}
}
// Database query offset
Public function start (){
Return ($ this-> page_id ()-1) * $ this-> page_size;
}

// Data output
Public function sqlquery (){
Return $ this-> SQL. "limit". $ this-> start (). ",". $ this-> page_size;
}

// Get the current file name
Private function php_self (){
Return $ _ SERVER ['php _ SELF '];
}

// Previous Page
Private function pre_page (){
If ($ this-> page_id () = 1) {// The number of pages equals 1
Return "php_self ()."? Page_id = 1 ". $ this-> url ()."> Previous Page ";
} Elseif ($ this-> page_id ()! = 1) {// The page number is not equal to 1
Return "php_self ()."? Page_id = ". ($ this-> page_id ()-1). $ this-> url ()."> Previous Page ";
}
}

// Display the page
Private function display_page (){
$ Display_page = "";
If ($ this-> page_num () <= 10) {// page smaller than 10
For ($ I = 1; $ I <= $ this-> page_num (); $ I ++) // The page is displayed cyclically.
$ Display_page. = "php_self ()."? Page_id = ". $ I. $ this-> url ()."> ". $ I ."";
Return $ display_page;
} Elseif ($ this-> page_num ()> 10) {// more than 10 pages
If ($ this-> page_id () <= 6 ){
For ($ I = 1; $ I <= 10; $ I ++) // The page is displayed cyclically.
$ Display_page. = "php_self ()."? Page_id = ". $ I. $ this-> url ()."> ". $ I ."";
Return $ display_page;
} Elseif ($ this-> page_id ()> 6) & ($ this-> page_num ()-$ this-> page_id ()> = 4 )){
For ($ I = $ this-> page_id ()-5; $ I <= $ this-> page_id () + 4; $ I ++) // The page is displayed cyclically
$ Display_page. = "php_self ()."? Page_id = ". $ I. $ this-> url ()."> ". $ I ."";
Return $ display_page;
} Elseif ($ this-> page_id ()> 6) & ($ this-> page_num ()-$ this-> page_id () <4 )){
For ($ I = $ this-> page_num ()-9; $ I <= $ this-> page_num (); $ I ++) // The page is displayed cyclically
$ Display_page. = "php_self ()."? Page_id = ". $ I. $ this-> url ()."> ". $ I ."";
Return $ display_page;
}
}
}

// Next page
Private function next_page (){
If ($ this-> page_id () <$ this-> page_num () {// The number of pages is less than the total number of pages
Return "php_self ()."? Page_id = ". ($ this-> page_id () + 1). $ this-> url ()."> Next Page ";
} Elseif ($ this-> page_id () = $ this-> page_num () {// The number of pages equals to the total number of pages
Return "php_self ()."? Page_id = ". $ this-> page_num (). $ this-> url ()."> Next Page ";
}
}

// Set paging information
Public function set_page_info (){
$ Page_info = "total". $ this-> datanum. "items ";
$ Page_info. = "php_self ()."? Page_id = 1 ". $ this-> url ()."> homepage ";
$ Page_info. = $ this-> pre_page ();
$ Page_info. = $ this-> display_page ();
$ Page_info. = $ this-> next_page ();
$ Page_info. = "php_self ()."? Page_id = ". $ this-> page_num (). $ this-> url ()."> last page ";
$ Page_info. = "". $ this-> page_id (). "/". $ this-> page_num (). "page ";
Return $ page_info;
}

}
?>
2. Script 2:
// Class usage
// Read the paging class
Include ("pager. class. php ");
// Database Connection Initialization
// $ Db = new mysql ();
$ Impeach_host = '10. 81.43.139 ';
$ Impeach_usr = 'vmtest15 ';
$ Impeach_passwd = 'vmtest15 ';
$ Impeach_name = 'ufeature ';
$ Impeach_con = mysql_connect ($ impeach_host, $ impeach_usr, $ impeach_passwd) or
Die ("Can't connect". mysql_error ());
Mysql_select_db ($ impeach_name, $ impeach_con );
// This is an SQL query statement and the query result is obtained.
$ SQL = "select word from ufeature. spam_accuse_word_list where flag = '0 '";
// Page initialization
$ Page = new pager ($ SQL, 20 );
// 20 is the number displayed on each page
// $ Res_1 = mysql_query ($ SQL) or
// Die ("Can't get result". mysql_error ());

$ Result = mysql_query ($ page-> sqlquery ());
While ($ info = mysql_fetch_array ($ result, MYSQL_ASSOC )){

// While ($ info = mysql_fetch_array ($ res_1, MYSQL_ASSOC )){
Echo $ info ["word"]."
";
}
// Page number index
Echo $ page-> set_page_info ();



?>
2. ajax

1. First, understand the limit usage in SQL statements.

SELECT * FROM table ...... Limit start position, number of operations (where the start position starts from 0)

Example:

Take the first 20 records: SELECT * FROM table ...... Limit 0, 20
Obtain 20 records FROM 11th: SELECT * FROM table ...... Limit 10, 20

LIMIT n is equivalent to LIMIT 0, n.

For example, select * from table LIMIT 5; // return the first five rows, the same as select * from table LIMIT

2. paging principle

The so-called paging display, that is, the result set in the database, is displayed in a segment

How to segment, the current segment (the number of lines per page, and the number of pages next)

First 10 records: select * from table limit 0, 10
11th to 20 records: select * from table limit 10, 10
21st to 30 records: select * from table limit 20, 10

Paging formula:

(Current page-1) X number of entries per page, number of entries per page
Select * from table limit ($ Page-1) * $ PageSize, $ PageSize

3. $ _ SERVER ["REQUEST_URI"] function

A type of predefined SERVER variables. all variables starting with $ _ SERVER are called SERVER variables.

REQUEST_URI is used to obtain the current URI, which is the complete address path after the domain name.

Example:

The current page is: http://www.test.com/home.php? Id = 23 & cid = 22

Echo $ _ SERVER ["REQUEST_URI"]

Result:/home. php? Id = 23 & cid = 22

4. parse_url () parses the URL function.

Parse_url () is a function that parses a URL into an array with a fixed key value.

Example
$ Ua = parse_url ("http: // username: password @ hostname/path? Arg = value # anchor ");
Print_r ($ ua );
Result:

Array
(
[Scheme] => http; protocol
[Host] => hostname; host domain name

[User] => username; user
[Pass] => password; password
[Path] =>/path; path
[Query] => arg = value; obtain the parameter

[Fragment] => anchor;
)

5. code example

The page for this message is divided into three parts: database design, connection page, and display page.

(1) design a database

The database name is bbs. there is a data table named message, which contains the title, lastdate, user, content and other fields, indicating the message title, message date, message recipient, and message content.

(2) connection page

$ Conn = @ mysql_connect ("localhost", "root", "123456") or die ("database link error ");
Mysql_select_db ("bbs", $ conn );
Mysql_query ("set names 'gbk'"); // use GBK Chinese encoding;

// Convert spaces and line breaks into HTML parses

Function htmtocode ($ content ){
$ Content = str_replace ("\ n ","
", Str_replace (" "," ", $ content); // Two str_replace nesting

Return $ content;
}

// $ Content = str_replace ("'", "'", $ content );
// Htmlspecialchars ();

?>

(3) display page

Include ("conn. php ");

$ Pagesize = 2; // set to display 2 records per page
$ Url = $ _ SERVER ["REQUEST_URI"];
$ Url = parse_url ($ url );
$ Url = $ url [path];

$ Numq = mysql_query ("SELECT * FROM 'message "');
$ Num = mysql_num_rows ($ numq );

If ($ _ GET [page]) {
$ Pageval = $ _ GET [page];
$ Page = ($ pageval-1) * $ pagesize;
$ Page. = ',';
}
If ($ num> $ pagesize ){
If ($ pageval <= 1) $ pageval = 1;

Echo "$ num total ".
"Next page of the previous page ";
}
$ SQL = "SELECT * FROM 'message' limit $ page $ pagesize ";
$ Query = mysql_query ($ SQL );

While ($ row = mysql_fetch_array ($ query )){
?>

Title:	Time:
User:
Content:

}
?>
(4) Last display


Method 3:

Script
Function viewpage (p ){
If (window. XMLHttpRequest ){
Var xmlReq = new XMLHttpRequest ();
} Else if (window. ActiveXObject ){
Var xmlReq = new ActiveXObject ('Microsoft. xmlhttp ');
}
Var formData = "page =" + p;
XmlReq. onreadystatechange = function (){
If (xmlReq. readyState = 4 ){
Document. getElementByIdx_x ('content2'). innerHTML = xmlReq. responseText;
}
}
XmlReq. open ("post", "pai_list.php", true );
XmlReq. setRequestHeader ("Content-Type", "application/x-www-form-urlencoded ");
XmlReq. send (formData );
Return false;
}
Script

Script 2:


Header ("Content-Type: text/html; charset = GB2312 ");
$ Pagesize = 10;
// Echo $ _ POST ['Page'];
$ Result = mysql_query ("Select count (DISTINCT region name) FROM". TBL_HOTELS );
$ Myrow = mysql_fetch_array ($ result );
$ Numrows = $ myrow [0];

$ Pages = intval ($ numrows/$ pagesize );
If ($ numrows % $ pagesize)
$ Pages ++;
If (isset ($ _ POST ['Page']) {
$ Page = intval ($ _ POST ['Page']);
}
Else {
// Set it to the first page
$ Page = 1;
}
$ First = 1;
$ Prev = $ page-1;
$ Next = $ page + 1;
$ Last = $ pages;
// Calculate the record offset
$ Offset = $ pagesize * ($ page-1 );
// Read the specified number of records
$ Result = mysql_query ("select 'Partition name', count (*) from". TBL_HOTELS. "group by 'Partition name' order by id desc limit $ offset, $ pagesize ");
$ Num = mysql_num_rows ($ result );
While ($ row = mysql_fetch_array ($ result, MYSQL_NUM )){
$ Pipeline name [] = $ row [0];
$ Countpeople [] = $ row [1];
}
For ($ a = 0; $ a <$ num; $ a ++)
{
// $ Result = mysql_query ("select count (title) from ". TBL_Comments. "where 'title' = \"". $ title [$ a]. "\"");
// $ Row = mysql_fetch_row ($ result );
Echo"

\ N ";Echo" \ N ";Echo" \ N ";Echo" \ N ";Echo" \ N ";Echo" \ N ";Echo" \ N ";Echo"

\ N "; // Rating_bar ($ title [$ a], 5 ); Echo"	$ Pipeline name [$ a] \ n "; Echo"
	\ N "; Echo "recommended users: ($ countpeople [$ a]) | \ n "; Echo"Average score:(". $ Count.") | number of comments :()\ N "; Echo"

\ N ";
}
Echo" Echo "border = 0> ";
Echo"";
Echo "";
Echo"

". $ Page." page/total ". $ pages." page | total ". $ numrows." | ";
If ($ page> 1) echo "homepage | ";
If ($ page> 1) echo "previous page | ";
If ($ page <$ pages) echo "next page | ";
If ($ page <$ pages) echo "last page ";
Echo "toPage";
Echo"

";