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mysql方式操作文本数据库

悬赏分：20 - 2008年03月14日

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。
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))
return $value;
return false;
}
function num_rows($result) {
return count($result);
}

/**
* 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$regs[3];\");
for($i=0;$i $rs[$key[$i]] = $value[$i];
$this->conn[$regs[1]][] = $rs;
$this->_close();
}
function _update($query) {
eregi(\"update +([0-9a-z_]+) +set *(,?.*=.*)+( +where +(.+))\",$query,$regs);
$regs[2] = eregi_replace(\",\",\"=\",$regs[2]);
$v = split(\"=\",$regs[2]);
$keys = $this->_where($regs[4],\"\\$this->conn[$regs[1]]\");
while(list($key,$value) = each($keys)) {
for($i=0;$i $this->conn[$regs[1]][$value][$v[$i]] = eregi_replace(\"\'\",\"\",$v[$i+1]);
}
$this->_close();
}
function _delete($query) {
eregi(\"delete +from +([0-9a-z_]+) *(where +(.+))?\",$query,$regs);
$keys = $this->_where($regs[3],\"\\$this->conn[$regs[1]]\");
while(list($key,$value) = each($keys)) {
unset($this->conn[$regs[1]][$value]);
}
reset($this->conn[$regs[1]]);
while(list($key,$value) = each($this->conn[$regs[1]])) {
$ch[] = $value;
}
$this->conn[$regs[1]] = $ch;
$this->_close();
}
function _where($search,$table) {
$search = eregi_replace(\"\$\",\" ( \",$search);
$search = eregi_replace(\"\$\",\" ) \",$search);
$search = eregi_replace(\"\\+\",\" + \",$search);
$search = eregi_replace(\"\\*\",\" * \",$search);
while(eregi(\"[^ ]([*/> $search = eregi_replace($regs[1],\" $regs[1] \",$search);
}
while(eregi(\"([> $search = eregi_replace($regs[1],eregi_replace(\" \",\"\",$regs[1]),$search);
}
$search = eregi_replace(\" \",\" \",trim($search));
$search = eregi_replace(\" and \",\" && \",$search);
$search = eregi_replace(\" or \",\" || \",$search);
$search = eregi_replace(\" = \",\" == \",$search);
$ar = split(\" \",$search);
eval(\"\\$t=$table;\");

for($i=0;$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 = \"\";

/** 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;
}
?>

测试例：
//require_once \"db_text.php\";

$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\");

print_r($rt);

?>

提问者： 03-14 16:04

答复

路过，帮顶

回答者：玉米づ冰冻可乐 - 2007-05-12