在两列中合并两个选择语句? [英] combine two select statement in two column?

问题描述

我有两个选择语句

1

select Start_Date
    from table1  where Start_Date not in (
    select End_Date
    from table1)

2

 select End_Date from table1
    where End_Date not in (
        select Start_Date
            from table1
        )

当我使用union时，我想在不同的列中合并两个select语句，它给我一个列并包含两个查询的结果，我希望每个查询的结果都在不同的列中，但是当我使用那样的内部联接时

i want to combine two select statement in different column when i use union all it give me one column with the result of two queries i want each query result in different column but when i use inner join like that

select a.End_Date , b.Start_Date from
( select End_Date from table1
where End_Date not in (
select Start_Date
from table1
) ) a

join

(select Start_Date
from table1 where Start_Date not in (
select End_Date
from table1)
) b
on 1=1

每条记录给我带来的结果是重复四次，这将帮助我下一步做什么?

it giving me result every record is repeating four times help me what i do next ??

推荐答案

如果每个查询仅返回1行，则可以使用:

If each of your queries returns only 1 row you can use:

SELECT 
(select Start_Date
    from table1  where Start_Date not in (
        select End_Date
        from table1)
) AS StartDate,
 (select End_Date from table1
    where End_Date not in (
        select Start_Date
        from table1)
 ) AS EndDate

如果查询返回的行多于1行，则必须选择其他解决方案:

If your queries return more than 1 row you have to choose a different solution:

您可以使用UNION: (您将在另一列中使两个查询与"NULL"不对齐)

You can use UNION: (You'll have the two queries misaligned with "NULL" in the other column)

(select Start_Date, Null AS EndDate
    from table1  where Start_Date not in (
         select End_Date
         from table1)
) 
UNION
(select  Null As StartDate, End_Date 
    from table1
    where End_Date not in (
        select Start_Date
        from table1)
 ) 

您可以使用JOIN 如果您有一个要用作加入"的字段，则可以使用此字段；如果没有，则可以添加一个要加入的字段(但是您需要检查返回的数据以避免错误) 另外，您还必须检查哪种连接可能对您有利(内部-左侧-固定) 在示例中，我添加了一个要联接的字段并使用了内部联接:

You can use JOIN If you have a field to use as "Join On" you can use this field, if not you can add a field to join (but you need to check data returned to avoid errors) Also you have to check what kind of join may be good for you (Inner - Left - rigth) In the example I add a field to join and use an Inner Join:

SELECT Start_Date, End_Date
FROM
(select 1 as InnerId, Start_Date
    from table1  where Start_Date not in (
        select End_Date
        from table1)
) As Tab1
 INNER JOIN
 (select  1 as InnerId, End_Date from table1
    where End_Date not in (
        select Start_Date
        from table1)
 ) AS Tab2
USING(InnerId)

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