SQL Server 2005错误的输出

Question

I have 3 table stock,inward,issue

Stock table's columns and data :

part_no | part_name | totalqty
10100        ciol      30
112233       abc       20
123456       coper      50

inward table :

part_no | qty
123456   10
123456   20
10100    20
112233   15
10100    25

issue table :

part_no | qty
112233   20
112233   15
123456   10
112233   25
10100    40
10100    20

my desired output :

part_no | part_name  |inwardQty |issueQty
10100      coil         45     60
112233     abc          15     60
123456     coper        30     10

following is the query i have written,but not giving my desired output

select s.part_no,s.part_name,sum(i.qty) as inwardQty,sum(p.qty)as issueQty 
from stock s 
left join inward i on s.part_no = i.part_no
left join issue p on s.part_no = p.part_no 
group by 
    s.part_no,s.part_name

getting following output by this query :

part_no | part_name  |inwardQty |issueQty
10100      coil         90     120
112233     abc          45     60
123456     coper        30     20

Answer 1

The problem is that you're matching every row for inward with every row for issue , for which they're dealing with the same part. I think subqueries would be best here:

select s.part_no,s.part_name,i.qty as inwardQty,p.qty as issueQty 
from stock s 
left join
    (select part_no,sum(qty) as qty from inward group by part_no) i on s.part_no = i.part_no
left join
    (select part_no,sum(qty) as qty from issue group by part_no) p on s.part_no = p.part_no 

So now, there's only one (or zero) rows to join in each of the joins, and you don't get a cartesian product.

Answer 2

Try this query:

SELECT 
    s.part_no, s.part_name,
    InwardQty = (SELECT SUM(qty) FROM @inward i WHERE i.part_no = s.part_no),
    IssueQty = (SELECT SUM(qty) FROM @issue p WHERE p.part_no = s.part_no)
FROM 
    dbo.stock s 
GROUP BY
    s.part_no, s.part_name

Gives me exactly your desired output.