mysql方式操作文本数据库

在一些小型的应用中，完全没有必要使用大型数据库软件。自己做一个SQL解释器就能用数据库的方式来管理了。
这个解释器，能解释常用的SQL命令。你可以自行添加其他功能。
<?php
class DB_text {
var $conn;
var $classname = "db_text";
var $database;
function on_create() {
}
function connect($database_name) {
$this->database = $database_name;
if(! file_exists($database_name)) {
$this->conn = array();
$this->_close();
}
$fp = fopen($this->database,"r");
$this->conn = unserialize(fread($fp,filesize($this->database)));
fclose($fp);
}
function &query($query) {
if(eregi("select ",$query)) return $this->_select($query);
if(eregi("insert ",$query)) return $this->_insert($query);
if(eregi("delete ",$query)) return $this->_delete($query);
if(eregi("update ",$query)) return $this->_update($query);
return array();
}
function fetch_row(&$result) {
if(list($key,$value) = each($result))

数据挖掘论坛

/**
* query的辅助函数
*/
function _select($query) {
if(eregi("(order by (.+))",$query,$regs)) {
$order = $regs[2];
$query = eregi_replace($regs[1],"",$query);
}
if(eregi("(group by (.+))",$query,$regs)) {
$group = $regs[2];
$query = eregi_replace($regs[1],"",$query);
}
eregi("select .* from ([0-9a-z_]+) *(where +(.+))?",$query,$regs);
if($regs[3] != "") {
$keys = $this->_where($regs[3],"$this->conn[$regs[1]]");
while(list($key,$value) = each($keys)) {
$rs[] = $this->conn[$regs[1]][$value];
}
}else {
$rs = $this->conn[$regs[1]];
}
if($order) {
sscanf($order,"%s %s",$key,$type);
if(empty($type)) $type = "asc";
$this->_sort($rs,$key,$type);
}
return $rs;
}
function _insert($query) {
eregi("insert +into +([0-9a-z_]+) *(.+) *values? *(.+)",$query,$regs);
eval("$key=array$regs[2];");
eval("$value=array$regs[3];");

数据挖掘交友

数据挖掘实验室

for($i=0;$i<count($ar);$i++) {
if(isset($t[0][$ar[$i]]))
$ar[$i] = "$value[".$ar][$i]."]";
}
$expr = "$expl=(".join(" ",$ar).");";

while(list($key,$value) = each($t)) {
eval($expr);
if($expl)
$keys[] = $key;
}
return $keys;
}
function _sort(&$ar,$key=0,$mode="desc") {
global $cmp_key;
$cmp_key = $key;
if($mode == "asc")
usort($ar,_cmp_asc);
else
usort($ar,_cmp_desc);
}
function _close() {
$fp = fopen($this->database,"w");
fwrite($fp,serialize($this->conn));
fclose($fp);
}
}

/** 排序键
*/
$cmp_key = ""; 数据挖掘论坛

/** 排序用工作函数(降序 由usort()调用)
*/
function _cmp_desc($a,$b) {
global $cmp_key;
if ($a[$cmp_key] == $b[$cmp_key]) return 0;
return ($a[$cmp_key] > $b[$cmp_key]) ? -1 : 1;
}

/** 排序用工作函数(升序 由usort()调用)
*/
function _cmp_asc($a,$b) {
global $cmp_key;
if ($a[$cmp_key] == $b[$cmp_key]) return 0;
return ($a[$cmp_key] > $b[$cmp_key]) ? 1 : -1;
}
?> 数据挖掘工具

测试例：
<?php
//require_once "db_text.php";

数据挖掘交友

$conn = new DB_text;
$conn->connect("text1.txt");

$conn->query("insert into manage (id,title) values (10,"abcd")");
$conn->query("insert into manage (id,title) values (2,"43d")");
$conn->query("insert into manage (id,title) values (20,"tuu")");
$conn->query("update manage set id=101,test="a" where id=10");
//$conn->query("delete from manage where id="10"");
//$conn->query("delete from manage where id=10 or table="code"");

//$rt = $conn->query("select * from manage where id=101 or table="code" group by 1 order by 1 asc");
$rt = $conn->query("select * from manage group by 1 order by id desc"); 数据挖掘工具

print_r($rt);

?> 数据挖掘实验室