How to union one column only from multiple tables? - mysql

Question

I am finding it hard to frame the question so I will show what I am trying to do.
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
The result I would like is
Result (Name, Table1.Score, Table2.Score)
Jane 20 NULL
Jack 15 16
Jill 12 14
John NULL 11
Jake NULL 15
Can name become the primary key? Note that Jane occurs twice in table 1(could occur in table 2 as well) and I want to sum the score and make the name unique in that given table.

Answer 1

Here's one way to do it with UNION and SUM:
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
And here is the SQL Fiddle.
Good luck.

Answer 2

try this
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
and this will output :
NAME | SCORE1 |SCORE2
Jack | 15 | 16
Jane | 20 |(null)
Jill | 12 | 14
Jake | (null) | 15
John | (null) | 11
HERE SQLFIDDLE DEMO

Answer 3

Well, if MySQL had full outer join, you would use that. Here is an alternative method:
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
The idea is to get all information needed from each table, with the score in different columns, by using the union all and splitting the score into two separate columns.
The final group by brings them together with one row per id.

Answer 4

Try this:
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