一个PHP的MySQL、MySQLi、SQLite 三合一数据库操作类

        这个类，在很多地方都能看到。

<?php
//MySQL、MySQLi、SQLite 三合一数据库操作类
if(!defined('IN_CRONLITE'))exit();
$nomysqli=false;
if(defined('SQLITE')==true){
class DB {
var $link = null;
function __construct($db_file){
global $siteurl;
$this->link = new PDO('sqlite:'.ROOT.'includes/sqlite/'.$db_file.'.db');
if (!$this->link) die('Connection Sqlite failed.n');
return true;
        }
function fetch($q){
return $q->fetch();
}
function get_row($q){
$sth = $this->link->query($q);
return $sth->fetch();
}
function count($q){
$sth = $this->link->query($q);
return $sth->fetchColumn();
}
function query($q){
return $this->result=$this->link->query($q);
}
function affected(){
return $this->result->rowCount();
}
function error(){
$error = $this->link->errorInfo();
return '['.$error[1].'] '.$error[2];
}
}
}
elseif(extension_loaded('mysqli') && $nomysqli==false) {
    class DB {
        var $link = null;
        function __construct($db_host,$db_user,$db_pass,$db_name,$db_port){
            
            $this->link = mysqli_connect($db_host, $db_user, $db_pass, $db_name, $db_port);
            
            if (!$this->link) die('Connect Error (' . mysqli_connect_errno() . ') '.mysqli_connect_error());
            
            //mysqli_select_db($this->link, $db_name) or die(mysqli_error($this->link));
            
 
mysqli_query($this->link,"set sql_mode = ''");
 //字符转换，读库
mysqli_query($this->link,"set character set 'utf8'");
//写库
mysqli_query($this->link,"set names 'utf8'"); 
return true;
}
function fetch($q){
return mysqli_fetch_assoc($q);
}
function get_row($q){
$result = mysqli_query($this->link,$q);
return mysqli_fetch_assoc($result);
}
function count($q){
$result = mysqli_query($this->link,$q);
$count = mysqli_fetch_array($result);
return $count[0];
}
function query($q){
return mysqli_query($this->link,$q);
}
function escape($str){
return mysqli_real_escape_string($this->link,$str);
}
function insert($q){
if(mysqli_query($this->link,$q))
return mysqli_insert_id($this->link); 
return false;
}
function affected(){
return mysqli_affected_rows($this->link);
}
function insert_array($table,$array){
$q = "INSERT INTO `$table`";
$q .=" (`".implode("`,`",array_keys($array))."`) ";
$q .=" VALUES ('".implode("','",array_values($array))."') ";
if(mysqli_query($this->link,$q))
return mysqli_insert_id($this->link);
return false;
}
function error(){
$error = mysqli_error($this->link);
$errno = mysqli_errno($this->link);
return '['.$errno.'] '.$error;
}
function close(){
$q = mysqli_close($this->link);
return $q;
}
}
} else { // we use the old mysql
class DB {
var $link = null;
function __construct($db_host,$db_user,$db_pass,$db_name,$db_port){
$this->link = @mysql_connect($db_host.':'.$db_port, $db_user, $db_pass);
            
if (!$this->link) die('Connect Error (' . mysql_errno() . ') '.mysql_error());
            
mysql_select_db($db_name, $this->link) or die(mysql_error($this->link));
mysql_query("set sql_mode = ''");
//字符转换，读库
mysql_query("set character set 'utf8'");
//写库
mysql_query("set names 'utf8'"); 
return true;
}
function fetch($q){
return mysql_fetch_assoc($q);
}
function get_row($q){
$result = mysql_query($q, $this->link);
return mysql_fetch_assoc($result);
}
function count($q){
$result = mysql_query($q, $this->link);
$count = mysql_fetch_array($result);
return $count[0];
}
        function query($q){
return mysql_query($q, $this->link);
}
function escape($str){
return mysql_real_escape_string($str, $this->link);
}
function affected(){
return mysql_affected_rows($this->link);
}
function insert($q){
if(mysql_query($q, $this->link))
return mysql_insert_id($this->link);
return false;
}
function insert_array($table,$array){
$q = "INSERT INTO `$table`";
$q .=" (`".implode("`,`",array_keys($array))."`) ";
$q .=" VALUES ('".implode("','",array_values($array))."') ";
if(mysql_query($q, $this->link))
return mysql_insert_id($this->link);
return false;
}
function error(){
$error = mysql_error($this->link);
$errno = mysql_errno($this->link);
return '['.$errno.'] '.$error;
}
function close(){
$q = mysql_close($this->link);
return $q;
}
}
}
?>

使用示例：

$DB=new DB($host,$user,$pwd,$dbname,$port);//链接数据库
$fwqlist=$DB->query("SELECT * FROM auth_fwq");//获取数据
$conf=$DB->get_row("SELECT * FROM auth_config WHERE id='1' limit 1");//获取一条数据
$DB->query("insert into `auth_log` (`action`,`msg`) values ('".$action."','".$msg."')");//执行sql语句，插入数据
$numrows=$DB->count("SELECT count(*) from jbkm WHERE{$sql}");//计数
$rs=$DB->query("SELECT * FROM jbkm WHERE{$sql} order by id desc limit $offset,$pagesize");//多条数据
while($res = $DB->fetch($rs)){
var_dump($res);
}
if($DB->query("DELETE FROM jbkm WHERE kind='$kind'")==true){//删除数据
echo '<div class="box">清空成功.</div>';
}
if($DB->query("update `jbkm` set `beizhu`='$beizhu',`useip`='$useip',`isuse`='$state',`endtime`='$endtime' where id='$id'")){//修改数据
    echo '修改成功！';
}else{
    echo '修改失败！'.$DB->error();
}
$sql = $DB->query("select * from auth_configs");//获取kv例子
while($r = $DB->fetch($sql)){
    $configs[$r['k']] = $r['v'];
}