mysql - 在 union all 中使用 order by

Question

我有一个查询

select username,amount from employee
union all
select '' as username,sum(amount) from employee
order by cast(username as decimal)

用户名从 1000 开始

当我使用此查询时，它始终显示从最高用户名到最小用户名

我想将最小的用户名显示到最高的用户名

我为此做什么？

Answer 1

通过包含在子查询中来尝试，

SELECT *
FROM
    (
        SELECT username, amount from employee
        UNION ALL
        SELECT '' as username, sum(amount) from employee
    ) x
ORDER BY (CASE WHEN username = '' THEN 1 ELSE 0 END) ASC, 
          CAST(username AS SIGNED) ASC