即使连接表为空也显示行吗？

Question

如果我找回场馆与他们的关闭时间从另一个表像这样的列表：

$fullDate = date('Y-m-d H:i:s'); 

$query="SELECT 
venues.ID, 
venues.VENUE_NAME, 
locations.LOCATION, 
hrs.opening_day, 
hrs.opening_time, 
hrs.closing_time 
FROM venues 
INNER JOIN venue_types 
ON venues.VENUE_TYPE = venue_types.ID 
INNER JOIN locations 
ON venues.VENUE_LOCATION = locations.ID 
INNER JOIN hours_of_operation hrs 
    on hrs.venue_id = venues.id 
    and ((hrs.opening_day=date_format('$fullDate' - INTERVAL (closing_time<opening_time and time('$fullDate')<closing_time) DAY, '%a'))) 
GROUP BY venues.VENUE_NAME"; 

我得到的，我已经指定了打开/关闭时间某一天在hours_of_operation场馆的结果。无论当天hours_of_operation行是否为空，该如何显示所有场所？

谢谢！ :)

Answer 1

使用LEFT JOIN：

... 
LEFT JOIN hours_of_operation hrs 
...