<?php


class WpSqlBuilder
{    
    const WHERE     = ' WHERE ';
    const AND_WHERE = ' AND ';
    const OR_WHERE  = ' OR ';
    
    public function select($fields)
    {
        return new WpSqlSelectBuilder($fields);
    }
    
    public function insert($fields)
    {
        return new WpSqlInsertBuilder($fields);
    }
    
    public function update($table)
    {
        return new WpSqlUpdateBuilder($table);
    }
    
    public function deleteFrom($table)
    {
        return new WpSqlDeleteBuilder($table);
    }
}

abstract class WpStatementBuilder
{
    protected $sql;

    public function execute()
    {
        echo $this->sql;
    }
}

class WpSqlDeleteBuilder extends WpStatementBuilder 
{
    public function __construct($table)
    {
        $this->sql = 'DELETE FROM ' . $table;
    }
    
    public function where($variable, $value)
    {
        $this->sql .= " WHERE $variable = '$value'";
        return $this;
    }
}

class WpSqlUpdateBuilder extends WpStatementBuilder 
{
    
    public function __construct($table)
    {
        $this->sql = 'UPDATE ' . $table;
    }
    
    public function set($fields)
    {
        $lastValue = end($fields);
        $lastCol   = key($fields);
                     array_pop($fields);
                     
        $set = '';
                     
        foreach ($fields as $column => $value)
        {
            $set .= "$column = '$value', ";
        }
        
        $this->sql .= " SET $set $lastCol = '$lastValue'";
        
        return $this;
    }
    
    public function where($variable, $value)
    {
        $this->sql .= " WHERE $variable = '$value'";
        return $this;
    }
}

class WpSqlInsertBuilder extends WpStatementBuilder 
{
    private $values;
    
    public function __construct($fields)
    {
        $cols   = '';
        $values = '';
        $lastValue = end($fields);
        $lastCol   = key($fields);
                     array_pop($fields);
        
        foreach ($fields as $column => $value)
        {
            $cols   .= "$column, ";
            $values .= "'$value', ";
        }
        
        $this->values = " ($cols $lastCol) VALUES($values '$lastValue')";
        return $this;
    }
    
    public function into($table)
    {
        $this->sql = 'INSERT INTO ' . $table . $this->values;
        return $this;
    }
}

class WpSqlSelectBuilder extends WpStatementBuilder 
{  
    public function __construct($fields)
    {
        $this->sql = 'SELECT ' . $fields;
    }
    
    public function from($table, $as = null)
    {
        $this->sql .= ' FROM ' .$table . (isset($as) ? ' AS ' . $as : '');
        return $this;
    }
    
    public function andFrom($table, $as)
    {
        $this->sql .= ', ' .$table . (isset($as) ? ' AS ' . $as : '');
        return $this;
    }
    
    public function where($variable, $value, $type = null, $isString = true)
    {
        $this->sql .= (isset($type) ? $type : WpSqlBuilder::WHERE) . $variable . ' = ' . (($isString) ? "'$value'" : $value);
        return $this;
    }    
}

$fields = array('id' => 1, 'col' => 'etc.');
$table  = 'myTable';



$SqlBuilder = new WpSqlBuilder();

$SqlBuilder->deleteFrom($table)->where('id', 5)->execute();

$SqlBuilder->update('myTable')->set($fields)->where('id', 5)->execute();

$SqlBuilder->insert($fields)->into('myTable')->execute();

$SqlBuilder->select('*')->from($table, 'a')
                        ->andFrom($table, 'b')
                        ->where('id', 5, WpSqlBuilder::WHERE, false)
                        ->where('a.id', 'b.id', WpSqlBuilder::AND_WHERE, false)
                        ->execute();

                        
/*

DELETE FROM myTable WHERE id = '5'

UPDATE myTable SET id = '1',  col = 'etc.' WHERE id = '5'

INSERT INTO myTable (id,  col) VALUES('1',  'etc.')

SELECT * FROM myTable AS a, myTable AS b WHERE id = 5 AND a.id = b.id

*/
?>