Mysql 如何仅从多个表中合并一列?
我发现很难提出这个问题,所以我将展示我正在努力做的事情Mysql 如何仅从多个表中合并一列?,mysql,sql,union,Mysql,Sql,Union,我发现很难提出这个问题,所以我将展示我正在努力做的事情 Table1 (ID, Name, Score) 1 Jane 10 2 Jack 15 3 Jill 12 4 Jane 10 Table2 (ID, Name, Score) 1 John 11 2 Jill 14 3 Jack 16 4 Jake 15 我想要的结果是 Result (Name, Table1.Score, Table2.Score) Jane 20
Table1 (ID, Name, Score)
1 Jane 10
2 Jack 15
3 Jill 12
4 Jane 10
Table2 (ID, Name, Score)
1 John 11
2 Jill 14
3 Jack 16
4 Jake 15
我想要的结果是
Result (Name, Table1.Score, Table2.Score)
Jane 20 NULL
Jack 15 16
Jill 12 14
John NULL 11
Jake NULL 15
名称可以成为主键吗?请注意,Jane在表1中出现了两次(也可能出现在表2中),我希望将分数相加,并使名称在给定的表中唯一 这里有一种使用
UNION
和SUM
的方法:
SELECT T.Name, Sum(T.Score), Sum(T2.Score) Score2
FROM (SELECT Name, SUM(Score) score FROM Table1 GROUP BY Name) t
LEFT JOIN (SELECT Name, SUM(Score) score FROM Table2 GROUP BY Name) t2
ON t.Name = t2.Name
GROUP BY T.Name
UNION
SELECT T.Name, Sum(T2.Score), Sum(T.Score) Score2
FROM (SELECT Name, SUM(Score) score FROM Table2 GROUP BY Name) t
LEFT JOIN (SELECT Name, SUM(Score) score FROM Table1 GROUP BY Name) t2
ON t.Name = t2.Name
GROUP BY T.Name
这是我的答案
祝你好运。好吧,如果MySQL有
完整的外部连接,你会使用它。以下是另一种方法:
select id, name, MAX(score1) as score1, MAX(score2) as score2
from ((select id, name, score as score1, NULL as score2
from table1
) union all
(select id, name, null as score1, score as score2
from table1
)
) t
group by id, name
其思想是通过使用union-all
并将分数拆分为两个单独的列,从每个表中获取所需的所有信息,分数在不同的列中
最后的分组依据
将它们与每个id的一行放在一起。试试这个
select t1.name , sum(t1.score) as score1 ,sum(t2.score2) as score2 from Table1 as t1
left JOIN
(select name , score as score2 from Table2 )t2
on t1.name = t2.name
group by name
union all
select t2.name , sum(t1.score1) as score1, sum(t2.score) as score2 from Table2 as t2
left JOIN
(select name , score as score1 from Table1 )t1
on t2.name = t1.name
where score1 is null
group by name
---- if you want use the order add this "order by name" here in the end
这将输出:
NAME | SCORE1 |SCORE2
Jack | 15 | 16
Jane | 20 |(null)
Jill | 12 | 14
Jake | (null) | 15
John | (null) | 11
试试这个:
select
name = Table1.name,
sum(Table1.score) as score1,
sum(Table2.Score) as score2
from Table1
full outer join
Table2
ON
Table2.name = Table1.name
where Table1.name is not null
group by table1.name
UNION
select
name = Table2.name,
sum(Table1.score) as score1,
sum(Table2.Score) as score2
from Table1
full outer join
Table2
ON
Table2.name = Table1.name
where Table2.name is not null
group by table2.name
order by score1 desc, score2
如果你让名字独一无二,你会怎么对待同名的人呢?这不是我的数据库,设计也很糟糕,所以我添加了一个“用户”表来列出所有的名字。但是,如果有两个相同的名称,他们必须使用数字/首字母使其唯一。我有30多个表,如果没有名称表来解决这个问题,那将是一场灾难。