SQL - 存在、加入还是加入？

Question

我有 3 张桌子。 “期限”、“业绩”和“公司”。 TERM 表具有对 PERFORMANCE.ID 的引用，而 PERFORMANCE 具有对 COMPANY.ID 的外键。我如何才能获得只有表演，其中有：

terms >= now and not null
and only from specific company

╔════════════╦════╦═════════════╦════╦═════════╗
║ TERM       ║    ║ PERFORMANCE ║    ║ COMPANY ║
║ ========== ║ -> ║ =========== ║ -> ║ ======= ║
║ start_date ║    ║ price       ║    ║ name    ║
║ ...        ║    ║ ...         ║    ║ ...     ║
╚════════════╩════╩═════════════╩════╩═════════╝

Answer 1

SELECT *
FROM Perfomance a 
INNER JOIN Term b on a.XX = b.XX
INNER JOIN Company c on a.XX = c.XX
where
C.Name = ' '

Answer 2

试试这个：

SELECT T.start_date, P.price, C.name  
FROM PERFORMANCE P JOIN
     COMPANY C ON P.COMPANY.ID=C.ID JOIN
     TERM T ON T.PERFORMANCE.ID=P.ID

尝试详细了解JOINs。