sql - mysql中的if子句

Question

我想要一个mysql中if子句的简单例子。我不想考虑 else 情况，只考虑 if 子句

Answer 1

例如:

SELECT *,
       if (`date_last` IS NULL,prev_date,last_date) as date 
FROM `table_name` 
WHERE `id` = 2 
ORDER BY `date` DESC