SQL-如何从内部语句中选择TOP 5

Question

我有以下查询正常工作。

 SELECT * 
    FROM (
         SELECT * 
         FROM table 
         WHERE name IS NULL 
         ORDER BY date DESC 
         LIMIT 20
         ) AS T 
    ORDER BY date ASC;

我想要的是选择该sql select查询的前5条记录。 因此，根据我阅读的帖子，我只需要添加TOP5。请参见以下内容：

 SELECT TOP 5 * 
        FROM (
             SELECT * 
             FROM table 
             WHERE name IS NULL 
             ORDER BY date DESC 
             LIMIT 20
             ) AS T 
        ORDER BY date ASC;

不幸的是，mysql告诉我存在语法错误，但我不明白。 预先感谢您的答复。 干杯。 渣

Answer 1

只需添加另一个限制即可。

 SELECT * 
    FROM (
         SELECT * 
         FROM table 
         WHERE name IS NULL 
         ORDER BY date DESC 
         LIMIT 20
         ) AS T 
    ORDER BY date ASC
    LIMIT 5;

Answer 2

不是所有数据库都支持TOP子句

由于它仅用于限制结果数，因此您可以使用LIMIT

    SELECT  * 
    FROM (
        SELECT * 
        FROM table 
        WHERE name IS NULL 
        ORDER BY date DESC 
        LIMIT 20
    ) AS T 
    ORDER BY date ASC
    LIMIT 5;