Question

I have a table A.

|----+----|
| P  |  S |
|----+----|
| p1 |  1 |
| p2 |  7 |
| p3 | 14 |
| p4 | 23 |
| p5 |  1 |
|----+----|

and table B

|----+----|
|  S |  C |
|----+----|
|  1 | 21 |
|  5 | 21 |
| 23 | 21 |
|  1 | 30 |
|  7 | 90 |
|----+----|

I need to sort table A.

Sorting order:

A. TableA.S exists where  (TableA.S = TableB.S) and TableB.C = 21
B. TableA.P

Final Output:

|----+----|
| P  |  S |
|----+----|
| p1 |  1 |
| p4 | 23 |
| p5 |  1 |
| p2 |  7 |
| p3 | 14 |
|----+----|

This needs to be converted to DBIx::Class query.

I tried following:

Select tableA.P, tableA.S
from tableA left join tableB on tableA.S = tableB.S
where (tableB.C = 21 or tableB.C is NULL)
order by tableB.C, tableA.P

But I am missing somewhere to get the result where tableB.S is ‘7’.

Thanks.

Answer 1

This sorts by A.P for all the records in A a matching record is found in B then by A.P for the other records.

 SQL> select A.P
       , A.S
from A 
     left join B        
        on ( A.S = B.S 
             and B.C = 21)
order by nvl2(B.S, 'ZZZZZZZZZZ', A.P), A.P
/

  2    3    4    5    6    7    8  
P           S
-- ----------
p1          1
p4         23
p5          1
p2          7
p3         14

SQL>