Do yourself a SQL Interpreter _php Foundation

Do a SQL Interpreter yourself
In some small applications, there is no need to use large database software at all. Making a SQL interpreter of your own can be managed in a database way.
This interpreter explains the commonly used SQL commands. You can add other features yourself.

<?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))
return $value;
return false;
}
function Num_rows ($result) {
return count ($result);
}

/**
* Auxiliary functions for Query
*/
function _select ($query) {
if (eregi (. +)), $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. *" ([0-9a-z_]+) * (where + (. +))? ", $query, $regs);
if ($regs [3]!= "") {
$keys = $this->_where ($regs [3], "\ $this->conn[$regs [1]]");
while (the 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; $i <count ($key); $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 (the list ($key, $value) = each ($keys)) {
for ($i =0; $i <count ($v); $i +=2)
$this->conn[$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 (the list ($key, $value) = each ($keys)) {
unset ($this->conn[$regs [1]][$value]);
}
Reset ($this->conn[$regs [1]]);
while (the list ($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, $regs)) {
$search = Eregi_replace ($regs [1], "$regs [1]", $search);
}
while (Eregi ([><!] + =) ", $search, $regs)) {
$search = Eregi_replace ($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; $i <count ($ar); $i + +) {
if (Isset ($t [0][$ar [$i]])
$ar [$i] = "\ $value [". $ar] [$i]. "]";
}
$expr = "\ $expl = (". Join ("", $ar). ";

while (the 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);
}
}

/** sort key
*/
$cmp _key = "";

/** sort with work functions (descending by Usort ())
*/
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;
}

/** sorting with work functions (ascending is called by Usort ())
*/
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;
}
?>

Test Example:
<pre>
<?php
Require_once "db_text.php";

$conn = new DB_Text;
$conn->connect ("Text1.txt");

$conn->query ("INSERT into Manage (Id,title) VALUES (' ABCD ')");
$conn->query ("INSERT into Manage (Id,title) VALUES (2, ' 43d ')");
$conn->query ("INSERT into Manage (Id,title) VALUES (' Tuu ')");
$conn->query ("Update manage set id=101,test= ' 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-id desc");

Print_r ($RT);

?>
</pre>