private function _prepareColumns(array $columnArray)
	{
		if(count($columnArray) === 0)
		{
			throw new \Exception('The column method of the statement must called before!');
		}
		foreach($columnArray as $column)
		{
			$this->columns .= $column->getColumnName() . ', ';
		}
		$this->columns = rtrim($this->columns);
		$this->columns = rtrim($this->columns, ',');

		return $this;
	}
private function _prepareColumns(array $columnArray)
	{
		if(count($columnArray) === 0)
		{
			throw new \Exception('The column method of the statement must called before!');
		}
		foreach($columnArray as $column)
		{
			$this->columns .= $column->getColumnName() . ', ';
		}
		$this->columns = rtrim($this->columns);
		$this->columns = rtrim($this->columns, ',');

		return $this;
	}
private function _prepareColumns ( array $ columnArray ) { if ( count ( $ columnArray ) === 0 ) { throw new \ Exception ( 'The column method of the statement must called before!' ) ; } foreach ( $ columnArray as $ column ) { $ this -> columns .= $ column -> getColumnName ( ) . ', ' ; } $ this -> columns = rtrim ( $ this -> columns ) ; $ this -> columns = rtrim ( $ this -> columns , ',' ) ; return $ this ; }
Validate and prepare the columns property to set it to the query.

@param ColumnInterface[] $columnArray An array with ColumnInterface objects as elements.

@return $this The same instance to concatenate methods.
@throws \Exception When column method of statement was not invoked.
Validate and prepare the columns property to set it to the query .