PHP DB Class for MySQL

DB.php

<?php

class DB
{
	var $con = null;
	var $result 	= null;
	var $has_result = false;
	var $error 		= false;
	var $last_query;
	var $affected_rows;
	
	
	function __construct($config)
	{	
		$this->con	= new mysqli($config['host'], $config['user'], $config['pass'], $config['name']);
		if ($this->con->connect_error)
		{
		    die('Connect Error (' . $mysqli->connect_errno . ') ' . $mysqli->connect_error);
		}
	}

	function select($table, $where_col = null, $where_val = null, $order = null, $limit = null){
		$query	= "SELECT * FROM `$table`";
		if($where_col){
			$where_val	= $this->escape($where_val);
			if(!is_numeric($where_val))
			{
				$where_val	= "'$where_val'";
			}

			$query .= " WHERE `$where_col` = $where_val";
		}
		if($order)
			$query .= " ORDER BY $order";
		if($limit)
			$query .= " LIMIT $limit";
		
		return $this->query($query);
	}
	function get_insert_id(){
		return $this->con->insert_id;
	}

	function &query($qry)
	{
		$this->clear();
		$this->result = $this->con->query($qry);
		$this->affected_rows	= $this->con->affected_rows;
		if($this->con->error)
		{
			$this->error	= $this->con->error;
		}
		$this->last_query	= $qry;
		$this->has_result	= is_object($this->result) && $this->result->num_rows > 0 && $this->affected_rows;
		return $this;
	}

	function query_scalar($qry)
	{
		$this->query($qry);

		if( !$this->has_result) return 0;

		$qry = $this->result->fetch_row();

		return $qry[0] ? $qry[0] : 0;

	}

	function result_list($col_index = 0){
		$data = array();
		if($this->has_result)
		{
			while($row = $this->result->fetch_row())
			{
				$data[] = $row[$col_index];
			}
		}
		return $data;	
	}
	
	function &result_array()
	{
		$data = array();
		if($this->has_result)
		{
			while($row = $this->result->fetch_assoc())
			{
				$data[] = $row;
			}
		}
		return $data;
	}
	function result_pair($name = 'name', $value = 'value'){
		$data = array();
		if($this->has_result)
		{
			while($row = $this->result->fetch_assoc())
			{
				$key	= $row[$name];
				$alias	= 0;
				while ( isset($data[$key]) ){
					$alias++;
					$key	= "{$row[$name]}_$alias";
				}

				$data[ $key ] = $row[$value];
			}
		}
		return $data;
	}
	function row_array()
	{
		if($this->has_result)
		{
			return $this->result->fetch_assoc();
		}else return array();
	}
	function delete($tbl, $where_col, $where_val = null)
	{
		$query	= "delete from `$tbl` where ";
		if(empty($where_val) && is_array($where_col))
		{
			$query	.= $this->parse_col_val($where_col);
		}else
		{
			$query	.= "`" . $this->escape($where_col) . "` = '" . $this->escape($where_val) . "'";
		}
		return $this->query($query);
	}
	function insert($tbl, &$data, $escape_val = true)
	{
		list($columns, $values)	= $this->parseColValues($data, $escape_val);
		if( $this->query("INSERT INTO `$tbl`($columns) VALUES ($values)")->affected_rows )
		{
			return $this->con->insert_id;
		}else return false;
	}

	function insertUpdate($tbl, &$data, $escape_val = true)
	{
		list($columns, $values)	= $this->parseColValues($data, $escape_val);
		$cols	= array_keys($data);
		//We think first col is a unique id, so we remove it
		array_shift($cols);
		foreach ($cols as &$col){
			$col	= "`$col` = VALUES(`$col`)";
		}
		$query	= "INSERT INTO `$tbl`($columns) VALUES ($values) " . 
					'ON DUPLICATE KEY UPDATE ' . implode(', ', $cols);
		return $this->query($query)->affected_rows;		
	}


	function replace($tbl, &$data, $escape_val = true)
	{
		list($columns, $values)	= $this->parseColValues($data, $escape_val);
		if( $this->query("REPLACE INTO `$tbl`($columns) VALUES ($values)")->affected_rows )
		{
			// if 1 == new insert, 2 == old deleted, new inserted
			return $this->con->insert_id;
		}else return false;
	}
	function parseColValues(&$data, $escape_val = true){
		$values	= $this->parseValues($data, $escape_val);
		return [ implode(', ', array_keys($values)), implode( ', ', $values ) ];
	}
	function parseValues(&$data, $escape_val = true){
		$values	= array();

		if($escape_val)
		{
			foreach ($data as $key => $val)
			{
				$values["`$key`"]	= is_numeric($val)? $val : "'" . $this->escape($val) . "'";
			}
		}else
		{
			foreach ($data as $key => $val)
			{
				$values["`$key`"]	=  is_numeric($val)? $val : "'" . $val . "'";
			}
		}
		return $values;
	}

	function update($tbl, $col, $val, $where_col = null, $where_val = null)
	{
		$query	= "update $tbl set ";
		if(is_array($col))
		{
			$query	.= $this->parse_col_val($col) . ' where ';
			if(is_array($val)){
				$query	.= $this->parse_col_val($val);
			}elseif(!empty($val) && !empty($where_col) ){
				$query	.= "`$val` = '" . $this->escape($where_col) . "'";
			}else{
				throw new Exception("Invalid argument", 1);
				
			}
			 
		}elseif(is_string($col) && is_string($where_col) && !empty($where_col))
		{
			$query	.= "`$col` = '" . $this->escape($val) . 
					"' where `$where_col` = '" . $this->escape($where_val) . "'";
		}else
		{
			throw new Exception("Ambigous update query, Iam confused :-(", 1);
			return false;
		}
		$this->query($query);
		return	$this->error ? false : $this->affected_rows;
	}
	private function parse_col_val($array)
	{
		$cols = array();
		foreach ($array as $c => &$v)
		{
			$cols[] = "`$c` = '" . $this->escape($v) . "'";
		}
		return implode(', ', $cols);
	}

	function clear()
	{
		if(is_object($this->result))
			$this->result->free_result();
		$this->affected_rows= 0;
		$this->result 		= null;
		$this->has_result	= false;
		$this->error		= false;
	}

	function escape($str)
	{
		return $this->con->escape_string($str);
	}
	function real_escape($str)
	{
		return $this->con->real_escape_string($str);
	}
	
	function close()
	{
		$this->clear();
		$this->con->close();
	}
}