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php数据库操作类，实现表的增删改查，获取行数，查询多条数据记录，左连接查询，创建数据表结构等。功能丰富，方便移值，有需要的朋友，可以参考下。

php数据库类完整代码与示例如下。

1、代码

<?php
/**
*
* 数据操作类
* @author Xiaoqiang
* @link http://bbs.it-home.org
*/
class Db {

var $links;
// 构造函数，初始化数据库（主机,用户名,密码,数据库名）
function __construct() {

$this->links = mysql_connect(DB_HOST, DB_USER, DB_PWD);
if(DEBUG){
mysql_select_db(DB_NAME) or die('ERROR:'.mysql_error());
}
else{
mysql_select_db(DB_NAME);
}
$char_sql = "SET NAMES '" . CHARSET . "'";
$this->query($char_sql);
}

/**
* ****************** 操作 ******************
*/
/**
* 增删改查操作方法
* 输入sql语句
* 返回布尔值或结果集$row
*/
function query($sql) {
if(DEBUG){
$render = mysql_query($sql) or die('query ERROR:'.mysql_error()."<br>sql语句出错：" . $sql);
return $render;
}
else{
return mysql_query($sql);
}
}
/**
* 计算行数方法
* 输入
* 结果数组
*/
function count($table,$condition='1') {

$sql = "select count(*) from `".DB_PREFIX.$table."` where $condition";
$result = $this->select($sql);
return $result[0]['count(*)'];
}
/**
* 原始的sql语句查操作方法
* 输入sql语句
* 结果数组
*/
function select($sql) {
$row = $this->query($sql);
$results = array();
while($arr = $this->fetch($row)){
$results[] = $arr;
}
//$this->free_result($row);
return $results;
}

/**
* 检查某字段是否存在某值
* @param 输入表名.字段,值
* @return id 或者 false
**/
function check_exists($table,$val){
$render = false;
$tab = explode('.',$table);
if($tab['1'] && $tab['1']!='id'){
$fields = $tab['1'];
$table = "{$tab[0]}.id,{$fields}";
}
else{
$fields = 'id';
$table = $tab[0].".id";
}
$condition = "`$fields` = '{$val}'";
$detail = $this->read($table,$condition);
if($detail[$fields]){
$render = $detail['id'];
}
return $render;
}

/**
* 查询多条数据方法
* 输入表名.字段，字段;查询条件，条数
* 如果条件是数组，则进入高级搜索模式
* 返回结果数组
*/
function readall($table,$condition='1',$limit='') {
$tab = explode('.',$table);
$table = $tab['0'];
if($tab['1']){
$fields = $tab['1'];
$fields_array =explode(',',$fields);
$fields = '';
foreach( $fields_array as $one){
$fields .= "`$one`,";
}
$fields = rtrim($fields,',');
}
else{
$fields = '*';
}
if(is_array($condition)){
$condition = $this->parse_condition($condition);
}
$sql = "select $fields from `".DB_PREFIX.$table."` where $condition";
if($limit)$sql .= " limit $limit";
return $this->select($sql);
}
/**
* 查询单条数据方法
* 输入表名.字段，字段;查询条件
* 返回结果数组
*/
function read($table,$condition='1') {
$render = $this ->readall($table,$condition,1);
return $render[0];
}
/**
* 修改数据方法
* 输入表名，插入数据array('字段'=>'值'),条件
* 返回布尔值
*/
function update($table,$data,$condition ) {

$set = '';
foreach( $data as $key=>$val){
$set .= "`$key` = '".$val."',";
}
$set = rtrim($set,',');
if(is_array($condition)){
$condition = $this->parse_condition($condition);
}
$sql = "update `".DB_PREFIX.$table."` set $set where $condition";
return $this->query($sql);
}
/**
* 插入数据方法
* 输入表名，数据array('字段'=>'值')
* 返回布尔
*/
function insert($table,$data) {

$fields = array();
$values = array();

foreach( $data as $key=> $val){
if(is_array($val)){
$_values = array();
$_fields = array();
foreach( $val as $k=> $v){
$_fields[]= "`$k`";
$_values[]= "'{$v}'";
}
$fields = $_fields;
$values[] = '('.implode(',',$_values).')';
}
else{
$fields[] = "`$key`";
$values[] = "'{$val}'";
}
}
$fields = implode(',',$fields);
$values = implode(',',$values);
$sql = "insert into `".DB_PREFIX.$table."` ($fields) values($values)";
return $this->query($sql);
}
/**
* 删除数据方法
* 输入表名，条件
* 返回bool
*/
function delete($table,$condition) {

if(empty($condition)){
die('条件不能为空');
}
if(is_array($condition)){
$condition = $this->parse_condition($condition);
}
$sql = "delete from `".DB_PREFIX.$table."` where $condition";
return $this->query($sql);
}
/**
* 解析条件的函数
* @param 条件数组
* <code>
$arr[] = "`id`==0";
$arr[] = "`id`==5";
$arr['id'] = "5";
$arr['or'][] = "`id`!=2";
$arr['or'][] = "`id`!=1";
$arr['or'][] = "`id`!=2";
$arr['groups'][]='id';
$arr['orders']['id']='asc';
$arr['orders']['td']='DESC';
* </code>
* @return str
**/
function parse_condition($condition){
$and = '1';
$or = '0';
$groups = array();
$orders = array();
foreach( $condition as $key=>$val){
if(is_numeric($key)){
$and .= " and $val";
}
elseif(strtolower($key)== 'or'){
//处理or条件
if(is_array($val)){
foreach( $val as $k=>$v){
if(is_numeric($k)){
$or .= " or {$v}";
}
elseif(is_array($v)){
$v = implode(',',$v);
$or .= " or `$k` in ($v)";
}else{
$or .= " or `$k='{$v}'";
}
}

}else{
$or .= " or $val'";
}
}
elseif(strtolower($key)== 'groups'){
//处理group by
foreach( $val as $k=>$v){
$groups[] = $v;
}

}elseif(strtolower($key)== 'orders'){
//处理order by
foreach( $val as $k=>$v){
$orders[] = $k.' '.$v;
}

}else{
if(is_array($val)){
$val = implode(',',$val);
$and .= " and `$key` in ($val)";
}else{
$and .= " and `$key`='{$val}'";
}
}
}
if($and!='1' && $or!='0')$where = $and.' or '.$or;
elseif($and!='1') $where = $and;
elseif($or!='0') $where = $or;
if($groups)$where .= " group by ".implode(',',$groups);
if($orders)$where .= " order by ".implode(',',$orders);
$where = str_replace('1 and','',str_replace('0 or','',$where));

return $where;
}
/**
* 锁表方法
* 输入表名，锁定类型，r or w 写锁要放在读锁前面
* 返回bool
*/
function lock($table,$type='r') {

if($type=='r'){
$type = 'READ';
}
else{
$type = 'WRITE';
}
$sql = "lock table `".DB_PREFIX.$table."` $type";
return $this->query($sql);
}
/**
* 解锁表方法
*
* 返回bool
*/
function unlock( ) {

$sql = "unlock tables";
return $this->query($sql);
}
/**
* 结果集放入数组方法
* 返回数组，指针下移
*/

function fetch($row) {
return mysql_fetch_array($row,MYSQL_ASSOC);
}

/**
* 计算结果集行数方法
* 输入$row
* 返回行数
*/
function num_rows($row) {
return mysql_num_rows($row);
}

/**
* 计算结果集列数方法
* 输入$row
* 返回列数
*/

function num_fields($row) {
return mysql_num_fields($row);
}

/**
* 释放result结果集内存
* 返回布尔值
*/

function free_result($row) {
return mysql_free_result($row);
}

/**
* 查看指定表的字段名
* 输入表名
* 返回全部字段名数组
*/
function list_fields($table) {
$fields = mysql_list_fields(DB_NAME, DB_PREFIX.$table, $this->links);
$columns = mysql_num_fields($fields);

for ($i = 0; $i < $columns; $i++) {
$row[$i] = mysql_field_name($fields, $i);
}
return $row;
}

/**
* 查看数据库版本方法
*/
function version() {
return mysql_get_server_info();
}

/**
* 插入时查看插入ID
*/
function insert_id() {
return mysql_insert_id();

}
/**
* 分页方法
*/
function page($table,$condition='1',$pagesize=20,$id='page') {
$page = $_GET[$id];
if(!$page)$page= 0 ;
elseif(!is_numeric($page))die('分页出错');

//查找结果集
$p = $page * $pagesize;
$limit = $p.",".$pagesize;
$results = $this->readall($table,$condition,$limit);

//取得结果集行数
$num = $this->count($table,$condition);
//定义最后页 $maxpage
if ($num % $pagesize) {
$maxpage = (int) ($num / $pagesize +1);
} else
$maxpage = $num / $pagesize;
if(STATICS){
//从服务器端取得url信息

if($_GET[$id] === null){
$_SERVER["REQUEST_URI"] = str_replace('index.php','',$_SERVER["REQUEST_URI"]);
$_SESSION[$id] = str_replace('.html','',$_SERVER["REQUEST_URI"],$count);
$_SESSION[$id] = $count?$_SESSION[$id] :$_SESSION[$id].'index';
if(!sizeof($_GET))$_SESSION[$id].="-htm";
}
$str = "<div class=pg style=padding-top:25px;>First ";
if($page)$str .= "Previous ";
if($page-3>=0)$str .="".($page-2)." ";
if($page-2>=0)$str .="".($page-1)." ";
if($page-1>=0)$str .="".$page." ";
if($page < $maxpage)$str .=($page+1)." ";
if($page+1 < $maxpage)$str .="".($page+2)." ";
if($page+2 < $maxpage)$str .="".($page+3)." ";
if($page+3 < $maxpage)$str .="".($page+4)." ";
if($page+1 < $maxpage)$str .="Next ";
if(!$maxpage)$maxpage=1;
$str .="Last  ".($page+1)."/".$maxpage."Total </div>";
}
else{
//从服务器端取得url信息

if($_GET[$id] === null){
$_SESSION[$id] = $_SERVER["REQUEST_URI"];
if(!sizeof($_GET))$_SESSION[$id].="?p=1";

}

$str = "<div class=pg style=padding-top:25px;>First ";
if($page)$str .= "Previous ";
if($page-3>=0)$str .="".($page-2)." ";
if($page-2>=0)$str .="".($page-1)." ";
if($page-1>=0)$str .="".$page." ";
if($page < $maxpage)$str .=($page+1)." ";
if($page+1 < $maxpage)$str .="".($page+2)." ";
if($page+2 < $maxpage)$str .="".($page+3)." ";
if($page+3 < $maxpage)$str .="".($page+4)." ";
if($page+1 < $maxpage)$str .="Next ";
if(!$maxpage)$maxpage=1;
$str .="Last  ".($page+1)."/".$maxpage."Total </div>";
}
return array($results,$str);
}

/**
* 左连接多表查询
* @param
* @return
**/
function leftjoin($left,$right,$on,$condition,$limit=1){
$left = explode('.',$left);
$right = explode('.',$right);
$left['0'] = "`".DB_PREFIX.$left['0']."`";
$right['0'] = "`".DB_PREFIX.$right['0']."`";
if($left['1'] || $right['1']){
$fields = '';
if(!empty($left['1'])){
$_field = explode(',',$left['1']);
foreach( $_field as $one){
$fields.=$left['0'].'.`'.$one."`,";
}
}
if(!empty($right['1'])){
$_field = explode(',',$right['1']);
foreach( $_field as $one){
$fields.=$right['0'].".`".$one."`,";
}
}
$fields = rtrim($fields,',');
}
else{
$fields = '*';
}
$on = str_replace('\2',$right[0],str_replace('\1',$left[0],$on));
$condition = str_replace('\2',$right[0],str_replace('\1',$left[0],$condition));
$sql = "SELECT {$fields} FROM {$left[0]} LEFT JOIN {$right[0]} ON ( {$on} ) WHERE ( {$condition} ) LIMIT {$limit} ";

$query = $this->query($sql);
$field_num = mysql_num_fields($query);
while($arr = mysql_fetch_array($query,MYSQL_NUM)){
$_arr = array();
for( $i=0 ; $i<$field_num ; $i++ ){
$table = str_replace(DB_PREFIX,'',mysql_field_table($query, $i));
$field = mysql_field_name($query, $i);
$_arr[$table.'.'.$field] = $arr[$i];
}
$array[]=$_arr;

}
$array=$limit==1?$arrat[0]:$array;
return $array;
}
/**
* 用于创建一个表结构
* @param 表名，结构 array(字段，格式，注释) 表注释 索引array(字段，字段) 全文搜索(字段，字段)
* @return 打印
**/

function createTable($tablename,$data,$comment='',$key='',$fulltext=''){
$_key='';
$_type = '';
$_fulltext = '';
$tablename = DB_PREFIX.$tablename;
$sql = "CREATE TABLE IF NOT EXISTS `$tablename` (
`id` int(10) unsigned NOT NULL auto_increment COMMENT 'ID',
";
foreach( $data as $one){
switch($one[1]){
case '':
$_type = 'varchar(255)';
break;
case 'tinyint':
$_type = 'tinyint(1)';
break;
case 'time':
$_type = 'int(10)';
break;
default:

if(strpos($one[1],'.')!==false){
$_type = explode('.',$one[1]);
$_type = $_type[0].'('.$_type[1].')';
}
else{
$_type = $one[1];
}
break;
}
$sql.="`{$one[0]}` $_type NOT NULL COMMENT '{$one[2]}',
";
}

if(!empty($key)){
foreach( $key as $one){
$_key.="KEY `$one` (`$one`),
";
}
}
if(!empty($fulltext)){
foreach( $fulltext as $one){
$_key.="FULLTEXT `$one` (`$one`),
";
}
}

$sql.= $_key.$_fulltext."PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=".CHARSET." COMMENT '$comment';
";
if(!$_GET[sure]){

if(empty($_GET)){
$url = '?sure=1';

}
else{
$url = $_SERVER["REQUEST_URI"].'&sure=1';
}

echo "即将执行以下建表操作：<br><pre class="brush:php;toolbar:false">$sql确定

"; } elseif($_GET[sure] && $this->query($sql)){ echo "完成操作"; } else{ echo "操作失败：
>

$sql

"; } exit; } }; ?>

调用示例：

<?php
//实例
define("DB_HOST", 'localhost');
define("DB_USER", 'root');
define("DB_PWD", '');
define("DB_NAME", "test");
define("DB_PREFIX", "test_");
define('CHARSET', 'gbk'); // 编码
define("GEBUG", 1);

//建表
$Db=new Db();
$data[] = array('title','','标题');
$data[] = array('open','tinyint.1','是否公开');
$data[] = array('keyword','','关键词');
$data[] = array('content','text','内容');
$data[] = array('created','time','时间');
//$Db->createTable('article',$data,'文章表');
//增删改查
$data['title']='t';
$data['keyword']='k';
$Db->insert('article',$data);
$num = $Db->read('article.id','1 order by id desc');
$data['created'] = mktime()+$num['id'];
$Db->update('article',$data,"`id` =2");
$Db->delete('article',"`id` =3");
?>