Question

我想在一个查询中从两个SQL表中选择信息，但信息不相关，因此不存在潜在关节。

示例可以是以下设置。

tblMadrid

   id | name    | games | goals
    1 | ronaldo | 100   | 100
    2 | benzema | 50    | 25
    3 | bale    | 75    | 50
    4 | kroos   | 80    | 10

tblBarcelona

   id | name    | games | goals
    1 | neymar  | 60    | 25
    2 | messi   | 150   | 200
    3 | suarez  | 80    | 80
    4 | iniesta | 40    | 5

我想要一个查询，它给我以下内容：

name    | games | goals
messi   | 150   | 200
ronaldo | 100   | 100

我尝试遵循以下逻辑：Multiple select statements in Single query但以下代码无效：

USE Liga_BBVA

SELECT (SELECT name,
               games,
               goals
        FROM   tblMadrid
        WHERE  name = 'ronaldo') AS table_a,
       (SELECT name,
               games,
               goals
        FROM   tblBarcelona
        WHERE  name = 'messi')   AS table_b
ORDER  BY goals

对此有何建议？谢谢信息：足球的东西只是一个简化的例子。实际上，不可能将两个表放在一个并且拥有一个新的＆＃34;团队＆＃34;柱。这两个表有完全不同的结构，但我需要一些与这个例子的特征相符的东西。

Answer 1

您可以这样做：

 (select
    name, games, goals
    from tblMadrid where name = 'ronaldo')
 union
 (select
    name, games, goals
    from tblBarcelona where name = 'messi')
order by goals;

例如，请参阅：https://dev.mysql.com/doc/refman/5.0/en/union.html

Answer 2

如果您希望将记录分开并且不进行联合。
尝试下面的查询

SELECT (SELECT name,
               games,
               goals
        FROM   tblMadrid
        WHERE  name = 'ronaldo') AS table_a,
       (SELECT name,
               games,
               goals
        FROM   tblBarcelona
        WHERE  name = 'messi')   AS table_b
FROM DUAL

Answer 3

UNION声明是你的朋友：

SELECT   a.playername, a.games, a.goals
FROM     tblMadrid as a
WHERE    a.playername = "ronaldo"
UNION
SELECT   b.playername, b.games, b.goals
FROM     tblBarcelona as b
WHERE    b.playername = "messi"
ORDER BY goals;

Answer 4

只要列匹配，您就可以合并查询。

SELECT name,
       games,
       goals
FROM   tblMadrid
WHERE  id = 1
UNION ALL
SELECT name,
       games,
       goals
FROM   tblBarcelona
WHERE  id = 2

Answer 5

select name, games, goals
from tblMadrid where name = 'ronaldo'
union
select name, games, goals
from tblBarcelona where name = 'messi'
ORDER  BY goals

Answer 6

您可以组合两个表中的数据，按目标排名最高，然后选择前两个，如下所示：

<强>的MySQL

select *
from (
  select * from tblMadrid
  union all
  select * from tblBarcelona
) alldata
order by goals desc
limit 0,2;

SQL Server

select top 2 *
from (
  select * from tblMadrid
  union all
  select * from tblBarcelona
) alldata
order by goals desc;

如果你只想要梅西和罗纳尔多

select * from tblBarcelona where name = 'messi'
union all
select * from tblMadrid where name = 'ronaldo'

为了确保messi位于结果的顶端，您可以执行以下操作：

select * from (
  select * from tblBarcelona where name = 'messi'
  union all
  select * from tblMadrid where name = 'ronaldo'
) stars
order by name;

Answer 7

在这种情况下，使用union会有所帮助。

您还可以在始终返回true且与这些表中的数据无关的条件下使用join。参见下文

从tblMadrid选择tmd .name，tbc.goals tmd join tblBarcelona tbc on 1 = 1;

Answer 8

在这种情况下你可以使用UNION

select id, name, games, goals from tblMadrid
union
select id, name, games, goals from tblBarcelona

你必须维护所选列的顺序，即两个SQL中的id，名称，游戏，目标

SQL：一个查询中有两个select语句

8 个答案: