MySQL：查询1 - 8套试卷数据，无数据显示null并按时间倒序排列

假设试卷数据存储在名为exam的表中，包含字段id、name和time。可以使用左连接和子查询的方式获取试卷1-8的数据，并按照时间倒序排列。 ```sql SELECT n.id, n.name, e.time FROM (SELECT 1 AS id, '试卷1' AS name UNION ALL SELECT 2 AS id, '试卷2' AS name UNION ALL SELECT 3 AS id, '试卷3' AS name UNION ALL SELECT 4 AS id, '试卷4' AS name UNION ALL SELECT 5 AS id, '试卷5' AS name UNION ALL SELECT 6 AS id, '试卷6' AS name UNION ALL SELECT 7 AS id, '试卷7' AS name UNION ALL SELECT 8 AS id, '试卷8' AS name) n LEFT JOIN exam e ON n.id = e.id ORDER BY e.time DESC; ``` 以上SQL语句中，首先创建一个虚拟表n，包含id和name两个字段，代表试卷的编号和名称。然后使用LEFT JOIN将n表和exam表连接起来，通过id字段匹配试卷数据。最后使用ORDER BY对查询结果按照时间倒序排列，如果某套试卷无数据，则对应的time字段值为null。 ######[AI写代码神器 | 312点数解答 | 2024-05-20 08:06:01]