Mysql将两个表连接到一个输出中，但结果子查询返回多于1行

Question

I have two tables

first table is tableA:

+-----------+-------------+
| NIM       | TA          |
+-----------+-------------+
| 107032014 | A_2010/2011 |
| 107032014 | B_2010/2011 |
| 107032014 | A_2011/2012 |
| 107032014 | B_2011/2012 |
| 107032014 | A_2012/2013 |
+-----------+-------------+

and second table is tableB:

+-----------+---------+-------------+
| NIM       | subtot  |     TA2     |
+-----------+---------+-------------+
| 107032014 | 6550000 | A_2010/2011 |
| 107032014 | 6550000 | B_2010/2011 |
| 107032014 | 6550000 | A_2011/2012 |
+-----------+---------+-------------+

how do I join two tables into one output like this :

+-----------+-------------+-------------+
| NIM       | TA          | subtot      |
+-----------+-------------+-------------+
| 107032014 | A_2010/2011 | 6550000     |
| 107032014 | B_2010/2011 | 6550000     |
| 107032014 | A_2011/2012 | 6550000     |
| 107032014 | B_2011/2012 | 0           |
| 107032014 | A_2012/2013 | 0           |
+-----------+-------------+-------------+

i used select operation :
select *,(select subtot from tableB where NIM='107032014') as subtot from tableA where NIM='107032014';
but :

ERROR 1242 (21000): Subquery returns more than 1 row

Answer 1

You could use a left join by nim and ta :

SELECT    a.nim, a.ta, COALESCE(subtot, 0)
FROM      tablea a
LEFT JOIN tableb b ON a.nim = b.nim AND a.ta = b.ta

Answer 2

You can do what you want with a correlated subquery:

select a.*,
       (select subtot
        from tableB b
        where b.NIM = a.NIM and
              b.TA2 = a.TA
       ) as subtot
from tableA a
where a.NIM = '107032014';

Because you want 0 rather than NULL , you need a bit of extra work. Here is one method:

select a.*,
       (select coalesce(sum(subtot), 0)
        from tableB b
        where b.NIM = a.NIM and
              b.TA2 = a.TA
       ) as subtot
from tableA a
where a.NIM = '107032014';