mysql怎么查询序号中未出现的数据

可以使用以下SQL语句来查询序号中未出现的数据：

SELECT missing_numbers.numberFROM (    SELECT ones.number + tens.number * 10 + hundreds.number * 100 AS number    FROM (SELECT 0 AS number UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS ones    CROSS JOIN (SELECT 0 AS number UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS tens    CROSS JOIN (SELECT 0 AS number UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS hundreds) AS missing_numbersLEFT JOIN your_table ON missing_numbers.number = your_table.idWHERE your_table.id IS NULLORDER BY missing_numbers.number;

在这个SQL语句中，我们首先生成一个包含所有可能序号的临时表missing_numbers，然后左连接your_table表，通过判断your_table.id是否为NULL来确定序号中是否未出现的数据。最后按照序号进行排序输出。