phplibrary/core/query/query.php

<?php

require_once 'table.php';
require_once 'meta.php';

/**
 * Êëàññ äëÿ ñîñòàâëåíèÿ çàïðîñà
 */
class Query
{
    static $alias = 0;

    public $table;
    public $filter = array ();
    public $calc   = array ();
    public $order  = array ();    

    /**
     * Ñîçäàåò ïóñòîé çàðîñ
     */
    static function create()
    {
        return new Query();
    }

    /**
     * Ìåòàäàííûå òàáëèöû
     * @param string $name Èìÿ òàáëèöû
     */
    function getTableMeta($name) 
    {
    }
    
    /**
     * Ñîçäàåò íîâûé çàïðîñ
     * @param string $name Èìÿ òàáëèöû
     *
     * @return Query
     */
    public function from($name)
    {
        $result = clone $this;

        $table = new Table();
        $table->type  = 'simple';
        $table->name  = $name;
        $table->alias = "t" . self::$alias++;

        $result->table = $table;
        
        return $result;
    }
    
    /**
     * Äîáàâëÿåò ê çàïðîñó óñëîâèå
     * @param string $field Èìÿ ïîëÿ òàáëèöû
     * @param string $op Èìÿ îïåðàòîðà 
     * @param $value Çíà÷åíèå ïîëÿ
     *
     * @return Query     
     */
    public function filter($field, $op, $value)
    {
        $result = clone $this;
        $result->filter [] = $result->table->alias ."." . $field . $op . "'" . $value . "'";
        return $result;            
    }

    /**
     * @param string $e Âûðàæåíèå
     */
    public function calc($e)
    {
        $result = clone $this;
        $result->calc [] = $e;
        return $result;
    }

    public function joinOn($first, $e) 
    {
        $result = $this->compose($first, array ('filter', 'calc', 'order'));
        
        $e = strtr($e, array ("a." => $this->table->alias . ".", 
                              "b." => $first->table->alias . "."));

        $table = new Table ();
        $table->type  = 'join';
        $table->name  = $this->table->name;
        $table->alias = $this->table->alias;
        $table->join  = $first->table;
        $table->condition = $e;

        $result->table = $table;

        return $result;        
    }

    /**
     * Îáüåäèíÿåò ïàðàìåòðû äâóõ çàðîñîâ
     * @param Query $first 
     * @pram array $list Ñïèñîê ïàðàìåòðîâ
     * 
     * @return Query
     */
    private function compose(Query $first, array $list)
    {
        $result = new Query();
        foreach ($list as $name) {
            $result->$name = array_merge($this->$name, $first->$name);
        }
        return $result;
    }

    /**
     * Çàêîâû÷èâàåò çíà÷åíèå
     */
    public function quote ($value) 
    {
        return "'" . $value . "'";
    }

    /**
     * Êîìïèëÿöèÿ òàáëèöû
     * @param Table $table
     * 
     * @return string ×àñòü ñòðîêè SQL
     */
    private function table(Table $table)
    {
        if ($table->type == 'simple') {
            return $table->name ." AS ".$table->alias;
        }
        if ($table->type == 'join') {
            return $table->name ." AS ".$table->alias. " JOIN " . $this->table ($table->join) . " ON " . $table->condition;
        }
        return "";
    }

    /**
     * Êîìïèëÿöèÿ WHERE
     * 
     * @return string ×àñòü ñòðîêè SQL
     */
    private function where ()
    {
        return implode(" AND ", $this->filter);
    }  
        
    /**
     * Êîìïèëÿöèÿ çàïðîñà â SELECT SQL
     * 
     * @return string SQL âûðàæåíèå
     */
    public function select()
    {
        return "SELECT " 
               . ((!empty($this->calc))? implode (",", $this->calc): "*")
               . " FROM "  . $this->table($this->table)
               . ((!empty ($this->filter))? " WHERE " . $this->where() : "");
    }

    /**
     * Êîìïèëÿöèÿ â DELETE
     */
    public function delete()
    {
        return "DELETE FROM " . $this->table->name  
               . ((!empty ($this->filter))? " WHERE " . $this->where() : "");
    }

    private function add_prefix($prefix, $array) {
        $result = array();
        foreach ($array as $value) {
            $result [] = $prefix . $value;
        }
        return $result;
    }

    /**
     * Êîìïèëÿöèÿ â UPDATE
     * TODO: Ðàçíûå òèïû çàïðîñîâ Query->update(); Query->select(), Query->insert();!!
     * Âîçâðààùàþò statement
     */
    public function update($values)
    {            
        $pairs = array ();
        foreach ($values as $key => $value) { // 
            $pairs [] = $key . "=" . $this->quote ($value); 
        }
        return "UPDATE " . $this->table->name . " SET "
               . implode(",", $pairs) 
               . ((!empty($this->filter))? " WHERE " . $this->where() : "");
    }

    /**
     * Êîìïèëÿöèÿ â INSERT
     */
    public function insert($values)
    {
        return "INSERT INTO ". $this->table->name . "(" 
        . implode(",", array_keys($values)) 
        . ") VALUES (" . implode(",", array_map(array($this, 'quote'), array_values($values))) . ")";
    }
}

?>