sql - SQL 列合并和聚合函数

Question

我有一个包含两列的简单表（以及两列感兴趣的列，加上一个 ID）...我有一个 ajax 搜索，它只是在寻找关键字...然后将其发送到我的真实搜索...ajax搜索不在乎它们是什么，但它们需要是不同的......

如何将两列合并在一起：

City, Country

Krakow, Poland
Warsaw, Poland
Austin, USA
New York, USA
Prague, Czech Republic

所以我会得到

Keyword, Sideinfo

Krakow, Poland
Warsaw, Poland
Austin, USA
Prague, Czech Republic
USA, Country (only once)
Poland, Country
Czech Republic, Country

我尝试做一个 UNION 但我不确定我会如何做一个 WHERE LIKE 'keyword%'

希望这是有道理的...

Answer 1

尝试这个。

SELECT Keyword, SideInfo
FROM
(
    SELECT
        DISTINT City as Keyword, Country as SideInfo
    FROM Table

    UNION
    SELECT 
        DISTINCT Country, 'Country'
    FROM Table
) AS InnerQuery
Where Keyword LIKE '%blah%'

Answer 2

这应该这样做：

select distinct country Keyword,'Country' SideInfo from Cities
union all
select City Keyword,Country SideInfo from Cities