sql

<?php
$commands = array("DELETE FROM users WHERE  (user_id = 5)" ,
    "UPDATE users SET  (age = 10) WHERE  (user_id = 1)",
"DELETE FROM users WHERE  (id = 5)" ,
"UDATE users SET  (age = 10) WHERE  (user_id = 1)" );



//$commands = $_GET['commands'];

$usersDatabase = array();
$db = "";
$lastId = 0;
$errors = 0;
$insert = "/^(.*?)\s*INTO\s*(.*?)\s*\((.*?)\)\s*VALUES\s*\((.*?)\)$/";
$update = "/^(\w+)\s*(.*?)\s*SET\s*\((.*?)\s*=\s*(.*?)\)\s*WHERE\s*\((.*?)\s*=\s*(.*?)\)$/";
$delete = "/^(.*?)\s*FROM\s*(.*?)\s*WHERE\s*\((.*?)\s*=\s*(.*?)\)$/";

//model of a user
$user = array(
    "user_id",
    "login",
    "gender",
    "age"
);

function insert($insertionData) {
    $keys = preg_split("/,\s*/", $insertionData[3]);
    $values = preg_split("/,\s*/", $insertionData[4]);
    $user = array(
        "user_id" => $GLOBALS['lastId'],
        "login" => "",
        "gender" => "undefined",
        "age" => "undefined"
    );

    for($i = 0; $i < count($keys) ;$i++) {

        if($keys[$i] == "user_id") {
            if($GLOBALS['lastId'] < $values[$i]) {
                $GLOBALS['lastId'] = $values[$i];
            } else {
                $values[$i] = $GLOBALS['lastId'];
            }
        }
        $user[$keys[$i]] = $values[$i];
    }
    $GLOBALS['usersDatabase'][] = $user;
    $GLOBALS['lastId']++;
}

function update($updates) {
    $valueToUpdate = $updates[3];
    $value = $updates[4];
    $conditionId = $updates[5];
    $conditionValue = $updates[6];
    $found = false;
    foreach ($GLOBALS['usersDatabase'] as &$user) {
        if($user[$conditionId] == $conditionValue) {
            $user[$valueToUpdate] = $value;
            $found = true;
        }
    }
    if(!$found) {
        $GLOBALS['errors']++;
    }
}

function delete($deletions) {
    $key = $deletions[3];
    $value = $deletions[4];

    foreach ($GLOBALS['usersDatabase'] as $k => $v) {
        if($GLOBALS['usersDatabase'][$k][$key] == $value) {
            unset($GLOBALS['usersDatabase'][$k]);
        }
    }
}

//game loop
for($i = 0; $i < count($commands) ;$i++) {
    $currCommand = $commands[$i];
    preg_match($insert, $currCommand, $insertions);
    preg_match($update, $currCommand, $updates);
    preg_match($delete, $currCommand, $deletions);
    if($insertions) {
        $keys = preg_split("/,\s*/", $insertions[3]);
        $diff = array_diff($keys, $user);
        $values = preg_split("/,\s*/", $insertions[4]);
        if($insertions[1] != "INSERT" || count($keys) != count($values) ||
            !in_array("login", preg_split("/,\s*/", $insertions[3])) ||
             count($diff) != 0) {
            $errors++;
            continue;
        } else {
            if($insertions[2] != "") {
                if($db == "") {
                    $db = $insertions[2];
                }

                if($insertions[2] == $db) {
                    insert($insertions);
                }
            }
        }
    } elseif($updates) {
        if( !in_array($updates[3], $user) ||
            !in_array($updates[5], $user) ||
            $updates[1] != "UPDATE" ||
            $updates[6] == "" ||
            $updates[3] == 'user_id' ||
            $db != $updates[2] ||
            $db == "") {
            $errors++;
            continue;
        } else {
            //perform update
            update($updates);
        }
    } elseif($deletions) {
        if($deletions[1] != "DELETE" || $deletions[3] == "login" || !in_array($deletions[3], $user)) {
            $errors++;
            continue;
        } else {
            if(count($usersDatabase) == 0 || $deletions[2] != $db) {
                continue;
            }
            //perform deletion
            delete($deletions);
        }
    } else {
        $errors++;
    }
}
if(count($usersDatabase) == 0) {
    echo "You have " . $errors . " error/s";
} else {
    $table = "<table><thead><tr><th>user_id</th><th>login</th><th>gender</th><th>age</th></tr></thead><tbody>";
    foreach ($usersDatabase as $user) {
        $table .= "<tr><td>" . htmlspecialchars($user['user_id']) . "</td><td>" .
                               htmlspecialchars($user['login']) . "</td><td>" .
                               htmlspecialchars($user['gender']) . "</td><td>" .
                               htmlspecialchars($user['age']) . "</td></tr>";
    }
    $table .= '</tbody><tfoot><tr><td colspan="4">Errors=' . $errors .'</td></tr></tfoot></table>';

    echo $table;
}
//var_dump($usersDatabase);
?>