src/db/JoinClause.class.php
public function on($firstColumn, $operator, $secondColumn, $boolean = 'and', $where = false) {
		
		if ($where)
			$this->bindings[] = $secondColumn;
		
		if ($where && ($operator === 'in' || $operator === 'not in') && is_array($secondColumn)) {
			$secondColumn = count($secondColumn);
		}
		
		$this->clauses[] = compact('firstColumn', 'operator', 'secondColumn', 'boolean', 'where');
		
		return $this;
	}
public function on($firstColumn, $operator, $secondColumn, $boolean = 'and', $where = false) {
		
		if ($where)
			$this->bindings[] = $secondColumn;
		
		if ($where && ($operator === 'in' || $operator === 'not in') && is_array($secondColumn)) {
			$secondColumn = count($secondColumn);
		}
		
		$this->clauses[] = compact('firstColumn', 'operator', 'secondColumn', 'boolean', 'where');
		
		return $this;
	}
Add an "on" clause to the join.

@param string $first
@param string $operator
@param string $second
@param string $boolean
@param bool $where
@return \queryBuilder\JoinClause