MySQL INNER JOIN和SELECT

Question

我正在开发一个小型日历应用程序，并根据flaschenpost提供的答案练习MySQL查询以查找可用时间段

  

mysql show time slots avaliable and time slots busy from table

我正在逐步研究查询。我单独运行下面的查询，看看它究竟返回了什么。

(select 1 as place, 'Free' as name union select 2 as place, 'Booked' as name ) as d 
inner join bookingEvents b 

但是，我遇到了语法错误：

  

错误1064（42000）：您的SQL语法出错;

我也尝试过以下查询，但仍然遇到同样的错误。

   select (select 1 as place, 'Free' as name union select 2 as place, 'Booked' as name ) as d 

请帮忙。

Answer 1

这些是属于查询from部分的表。

这样做：

select 
    *
from
    (select 1 as place, 'Free' as name union select 2 as place, 'Booked' as name ) as d 
    inner join bookingEvents b 

Answer 2

您在第二个子查询中缺少from，因此您在任何表中都没有执行select语句。

在您提到的第二个查询中，只需将* from设为

select * from (select 1 as place, 'Free' as name union select 2 as place,'Booked' as name ) as d