Php+mysql Paging principle

1. Limit usage in SQL statements

SELECT * FROM table ... limit start position, number of operation bars (start position starting from 0)

SELECT * FROM Table ... limit 0, 20 (take front 20)

SELECT * FROM Table ... limit 10, 20 (starting from 11 fetch 20)

2. A formula for learning pagination

(1) Paging principle

The so-called paging display, that is, the result set in the database, a section of the display

(2) Required conditions

How to segment, current in the first paragraph (there are several pages per page, the current second page)

Top 10 Records: SELECT * FROM table limit 0,10

11th to 20th record: SELECT * FROM table limit 10,10

21st to 30th Record: SELECT * FROM table limit 20,10

(3) Get the formula

(Current page-1) x number of pages per page, number of articles per page

Select * FROM table limit ($Page-1) * $PageSize, $PageSize

3. Parse_url () Parse URL function

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

$ua =parse_url ("Http://username:[email protected]/path?arg=value#anchor");p Rint_r ($ua); Result: Array ([scheme] = HTTP [Host] = hostname [user] = username [pass] = password [path] +/path [query] = arg =value [Fragment] = anchor)

4.$_server["Request_url"] function

One of the predefined server variables, all at the beginning of the $_server, called Predefined server variables

Request_url is the function to get the current URL, but also the full address path in addition to the domain name

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

echo $_server["Request_url"]

Results:/home.php?id=23&cid=22