Question

我有一个很容易理解的问题，但对我来说，实现并不是那么简单。

我有一张名为时间的表格：

-----------------------------------
 DAY     TIME1     TIME2
-----------------------------------
 1       08.00     09.40
 1       09.40     10.00
 1       10.00     11.40
 2       08.00     08.50
 2       08.50     10.40
 ----------------------------------

我想得到的是：

-------------------
 DAY     TIME     
-------------------
 1       08.00     
 1       09.40     
 1       10.00     
 1       11.00     
 2       08.00     
 2       08.50     
 2       10.40     
 ------------------

我试过这段代码：

SELECT DISTINCT sub.val FROM (
  SELECT Time1 AS val FROM Time
  UNION ALL
  SELECT Time2 AS val FROM Time
) AS sub

它只返回时间列。我不知道加入“Day”专栏。当我试图在“DISTINCT sub.val”之后添加“Day”时，它出错了。怎么做？

非常感谢。

Answer 1

select distinct day, time1 from mytab
union
select distinct day, time2 from mytab

Answer 2

SELECT DISTINCT sub.Day, sub.val as Time FROM (
  SELECT Day, Time1 AS val FROM Time
  UNION ALL
  SELECT Day, Time2 AS val FROM Time
) AS sub

Answer 3

试试这个

SELECT DISTINCT *
FROM (
    SELECT day, time1 FROM Time
    UNION ALL SELECT day, time2 FROM Time
) AS x
ORDER BY x.day

Answer 4

这可能会有所帮助：

SELECT
    DAY,
    TIME1
FROM
    YourTable AS T
UNION
SELECT
    DAY,
    TIME2
FROM
    YourTable AS T
ORDER BY DAY,TIME1

在SQL中连接表上的两列

4 个答案: