Question

CREATE TABLE Countries(location varchar(255), country varchar(255))

INSERT INTO Countries(location, country)
               VALUES('Arkansas', 'US'),
                      ('Newyork', 'US'),
                      ('New Jersey', 'US'),
                      ('Tokyo', 'JP'),
                      ('Yokohama', 'JP'),
                      ('Chennai', 'IN'),
                      ('Delhi', 'IN'),
                      ('Sydney', 'AU'),
                      ('Melbourne', 'AU');

我需要查询以下输出

 Location     |         Country
--------------------------------
  Arkansas                US
  Tokyo                   JP
  Chennai                 IN
  Sydney                  AU
  Newyork                 US
  Yokohama                JP
  Delhi                   IN
  Melbourne               AU
  New Jersey              US

Answer 1

您需要根据其所在国家/地区的相对顺序为每个位置指定排名。你可以使用变量在MySQL中创建一个临时的rownumber函数：

SELECT  Country,
        Location,
        @r:= CASE WHEN Country = @c THEN @r + 1 ELSE 1 END AS RN,
        @c:= Country AS C2
FROM    Countries,
        (SELECT @r:= 1) r,
        (SELECT @c:= '') c
ORDER BY Country, Location;

这将输出

COUNTRY     LOCATION    RN  C2
AU          Melbourne   1   AU
AU          Sydney      2   AU
IN          Chennai     1   IN
IN          Delhi       2   IN
JP          Tokyo       1   JP
JP          Yokohama    2   JP
US          Arkansas    1   US
US          New Jersey  2   US
US          Newyork     3   US

然后您可以通过RN和国家/地区订购此产品以获得您想要的订单

SELECT  Location, Country
FROM    (   SELECT  Country,
                    Location,
                    @r:= CASE WHEN Country = @c THEN @r + 1 ELSE 1 END AS RN,
                    @c:= Country AS C2
            FROM    Countries,
                    (SELECT @r:= 1) r,
                    (SELECT @c:= '') c
            ORDER BY Country, Location
        ) c
ORDER BY rn, Country DESC;

<强> Example on SQL Fiddle

修改

由于您收到排序规则错误，但未指定排序规则错误的唯一方法，我希望纠正这一点是对所有内容使用显式排序规则：

SELECT Location, Country FROM ( SELECT Country COLLATE utf8_general_ci AS Country, Location COLLATE utf8_general_ci AS Location, @r:= CASE WHEN Country = @c THEN @r + 1 ELSE 1 END AS RN, @c:= Country COLLATE utf8_general_ci AS C2 FROM Countries, (SELECT @r:= 1) r, (SELECT @c:= '' COLLATE utf8_general_ci) c ORDER BY Country, Location ) c ORDER BY rn, Country DESC

<强> SQL FIDDLE

Answer 2

试试这个：

在mysql中使用按字段（）排序

select Location, Country
from Countries
order by Field(Location,'Arkansas','Tokyo','Chennai',...)

Answer 3

您可以使用oracle Analytical function rank（）

执行此查询

这是同一个

的工作查询

select tbl.l,
tbl.c
from
(
select location l,
country c,
rank() over (partition by country order by rowid) rnk
from countries
order by rowid,rnk) tbl
order by rnk,rowid;

Answer 4

如果没有id，您无法按照自己的方式订购表格。你可以这样创建你的表：

CREATE TABLE Countries(
  id INT NOT NULL AUTO_INCREMENT,
  location varchar(255),
  country varchar(255),
  PRIMARY KEY(ID))

然后你可以插入你的数据：

INSERT INTO Countries(location, country)
           VALUES('Arkansas', 'US'),
           ...

Ant然后我将使用标准SQL编写查询：

SELECT *
FROM Countries c1
ORDER BY (select count(*)
          from countries c2
          where c1.country=c2.country
          and c1.id>c2.id), id

这个查询可能不会很快，但它会起作用。但是，如果不使用id，则无法回答您的问题。 SQL表没有默认顺序，所以如果没有id就没有办法告诉它，例如，悉尼来到墨尔本之前，即使它是先插入的。

Answer 5

SELECT  Location, Country
  FROM  (SELECT  Country,Location,
                  @r:= CASE WHEN Country = @c THEN @r + 1 ELSE 1 END AS RN,
                  @c:= Country AS C2
            FROM  Countries,
                  (SELECT @r:= 1) r,
                  (SELECT @c:= '') c
        )c
 ORDER BY rn, Country DESC;

子查询中应该没有Order by

Answer 6

enter image description here

为什么会这样。

显示MySQL数据库错误：非法混合排序（latin1_general_ci，IMPLICIT）和（latin1_swedish_ci，IMPLICIT）进行操作'='

如何使用特定值的订单

6 个答案: