PHP on a, the next article implementation code and principle explanation _php skill

Implementation principle:

This is to sort the ID pair for the ORDER by id DESC or the orders by ID ASC, and then to judge the article that is more identical than the current id> or less than the current article ID.
The SQL statement for the instance is as follows:

$ID is the ID of the face article.

SELECT * FROM news where id< $id the ORDER by id DESC limit 0,1
SELECT * FROM news where id> $id the ORDER by id DESC limit 0,1

--
--The structure of the table ' String_find '
--

CREATE TABLE IF not EXISTS ' String_find ' (
' ID ' int (4) not NULL auto_increment,
' charList ' varchar default NULL,
PRIMARY KEY (' id ')
) Engine=myisam DEFAULT Charset=utf8 auto_increment=7;

--
--Export the data in the table ' String_find '
--

INSERT into ' string_find ' (' id ', ' charList ') VALUES
(1, ' cloud-dwelling community '),
(2, ' Baidu '),
(5, ' www.baidu.com '),
(6, ' www.jb51.net ');

All right, let's see how it's done.

Copy Code code as follows:

mysql_connect (' localhost ', ' root ', ' root ') or Die (Mysql_error ());
mysql_select_db (' cc ');
mysql_query ("Set names ' GBK '");
$cid =5;//is the number of your current article
$sql = "SELECT * from String_find where id> $cid the ORDER by id DESC limit 0,1"; Previous article
$sql 1 = "SELECT * from String_find where id< $cid the ORDER by ID ASC limit 0,1";//Next article

$result = mysql_query ($sql);
if (mysql_num_rows ($result))
{
$rs = Mysql_fetch_array ($result);
echo "Previous". $rs [0];
}
Else
{
echo "No";
}

$result 1 = mysql_query ($sql 1);
if (mysql_num_rows ($result 1))
{
$rs 1 = mysql_fetch_array ($result 1);
echo "Next". $rs 1[0];
}
Else
{
echo "No";
}

The following are the articles written by other netizens.
Because I want visitors to see the previous topic while browsing the web, the title of the next topic, so it must be queried in the database, can be taken by the limit limit, for example, my blog is automatically incremental by ID, you can find by looking at greater than or less than the current ID to fetch

$UpSQL = "SELECT * from ' blog ' WHERE ' id ' < $id ' id ' DESC LIMIT 0,1";
$DownSQL = "Select ' id ', ' Title ' from ' blog ' WHERE ' id ' > $id ' id ' ASC LIMIT 0,1";

And then through the query, take out the data
If only a single "previous", "next" then there is no need to query, this is not necessary to query, but perhaps the user will see after clicking, this is already the home page or this is the last page, hehe

Copy Code code as follows:

Switch ($act) {
Case "Up":
$SQL = "SELECT * from ' blog ' WHERE ' id ' < $id ' id ' DESC LIMIT 0,1";
Break
Case ' down ':
$SQL = "SELECT * from ' blogs ' WHERE ' id ' > $id order by ' ID ' ASC LIMIT 0,1";
Break
Default:
$SQL = "SELECT * from ' blog ' WHERE ' ID ' = $id LIMIT 0,1";
Break
}

To implement the previous topic by passing an action, the next topic