SQL联接无需联接关键字即可联接2个具有公共列的表

Question

t2我正在尝试不使用join关键字来联接2个表。两个表的数据类型相同，但是顺序不同。我想在两个表中的排名不同时显示两个表（即airport2017和airport2010）的排名，机场信息，否则跳过该行。不使用join关键字怎么办？

t1

Answer 1

我真的不确定这是否是您要查找的内容，但这会找到列出具有col_a和col_b列的两个表中的差异的列表：

    WITH
    aset AS
        (SELECT col_a, col_b FROM table_a
         MINUS
         SELECT col_a, col_b FROM table_b),
    bset AS
        (SELECT col_a, col_b FROM table_b
         MINUS
         SELECT col_a, col_b FROM table_a)
SELECT 'A unique records' AS TYPE, a.*
  FROM aset a
UNION ALL
SELECT 'B unique records' AS TYPE, a.*
  FROM bset a

Answer 2

虽然我不确定为什么要这样做，但是此查询将为您提供所需的信息：

select airport, max(rank2017) as Rank2017, max(Rank2018) as Rank2018 from 
(
    select airport, airportrank as rank2017, 0 as rank2018 from airport2017
    union
    select airport, 0 as rank2017, airportrank as rank2018 from airport2018
) tabs
group by airport

如果只希望排名已更改的那些，请在底部添加：

having max(rank2017)<>max(Rank2018)

Answer 3

这将在您希望使用join的情况下起作用：

select a.rank,a.airport from t1 a, t2 b
where a.rank=b.rank

谢谢。